DOR'S
CODING
SCHOOL
Learn To Program Workbook
EBOOK
Python Problems – Functions, Variables
Questions
Problem 1
Create a variable. Store your name in that variable. Print the variable.
Problem 2
Ask user for his name. Print only the name.
Problem 3
Ask user for his name. Print “Hello” and the name of the user.
Problem 4
Ask a user for his name. Print it using f-strings:
https://www.geeksforgeeks.org/formatted-string-literals-f-strings-python/
Problem 5
Create a variable ‘a’ and store the value 5. Create a variable ‘b’ and store the
value of ‘a’. Change the value of ‘a’ to 10. Print the variable ‘a’ and ‘b’.
Problem 6
Ask user for a title of a movie. Convert the first letters in every word of the
title of the movie in upper case. Print it.
Hint: See how title() method works (click here!)
Problem 7
Ask user for a title of a movie. Convert every word of the title of the movie in
upper case. Print it.
Hint: See how upper() method works (click here!)
2
Python Problems – Functions, Variables
Problem 8
Ask user for a title of a movie. Convert every word of the title of the movie in
lower case. Print it.
Hint: See how lower() method works (click here!)
Problem 9
Create a variable that holds the value “
whitespace and print it.
Hi everyone
“. Remove the
Hint: See how strip() method works (click here!)
Problem 10
Create a variable that holds the value “,,,,,rrtthh.....coding....rrr“. Remove the
extra characters and print only coding.
Hint: See how strip() method works (click here!)
Problem 11
Create a variable that holds the value “I love coding“. Replace the word coding
by Python. Print it.
Hint: See how replace() method works (click here!)
Problem 12
Ask user for two integers. Sum them and print the result.
Problem 13
Ask user for two float numbers. Sum them and print the result.
Problem 14
Ask user for two integers. Subtract them and print the result.
3
Python Problems – Functions, Variables
Problem 15
Ask user for two integers. Multiply them and print the result.
Problem 16
Ask user for two integers. Divide them and print the result.
Problem 17
Ask user for two numbers. Divide them and print the result with no decimal
places.
Hint: See how round() method works (click here!)
Problem 18
Ask user for two numbers. Multiply them. Print the result with only 2 decimal
places.
Hint: See how to do it (click here!)
4
Python Problems – Functions, Variables
Solutions
Problem 1
name = "Giovanna"
print(name)
Problem 2
name = input("What's your name? ")
print(name)
Problem 3
name = input("What's your name? ")
print(“Hello, “ + name)
Problem 4
answer = input("What's your name? ")
print(f"hello, {answer}")
Problem 5
a=5
b=a
a = 10
print(a)
print(b)
You should see a = 10 and b = 5.
5
Python Problems – Functions, Variables
Problem 6
movie = input("What's your favorite movie? ")
print(movie.title())
Problem 7
movie = input("What's your favorite movie? ")
print(movie.upper())
Problem 8
movie = input("What's your favorite movie? ")
print(movie.lower())
Problem 9
var = "
Hi everyone
"
print(movie.strip())
Problem 10
var = “,,,,,rrtthh.....coding....rrr“
print(movie.strip(“,.rth”))
Problem 11
var = “I love coding“
print(movie.replace(“coding”, “Python”))
6
Python Problems – Functions, Variables
Problem 12
x= input("x: ")
y= input("y: ")
sum = int(x) + int(y)
print(sum)
Problem 13
x= input("x: ")
y= input("y: ")
sum = float(x) + float(y)
print(sum)
Problem 14
x= input("x: ")
y= input("y: ")
result = int(x) - int(y)
print(result)
Problem 15
x= input("x: ")
y= input("y: ")
result = int(x) * int(y)
print(result)
7
Python Problems – Functions, Variables
Problem 16
x= input("x: ")
y= input("y: ")
result = int(x) / int(y)
print(result)
Problem 17
x= input("x: ")
y= input("y: ")
result = int(x) / int(y)
print(round(result))
Problem 18
x= input("x: ")
y= input("y: ")
result = int(x) * int(y)
print(“{:.2f}”.format(result))
8
Python Problems – Functions, Variables
Questions
Problem 1
Create a function that prints hello. Call the function.
Problem 2
Write a program to create a function that takes two arguments, name and age,
and print their value.
Problem 3
Create a function that returns double the input. Call the function multiple
times with different values. Print the result of each function call.
Problem 4
Ask user for two integers in the main function. Create a function that sum
them and return the result. Print the result in the main function.
Problem 5
Ask user for two float numbers in the main function. Create a function that
sum them and return the result. Print the result in the main function.
Problem 6
Ask user for two integers in the main function. Create a function that subtract
them and return the result. Print the result in the main function.
Problem 7
Ask user for two integers in the main function. Create a function that multiply
them and return the result. Print the result in the main function.
2
Python Problems – Functions, Variables
Problem 8
Ask user for two integers in the main function. Create a function that divides
the two integers and return the result. Print the result in the main function.
Problem 9
Ask user for two numbers in the main function. Create a function that divides
them and return the result. Print the result with no decimal places in the main
function.
Hint: See how round() method works (click here!)
Problem 10
Ask user for two numbers in the main function. Create a function that divides
the two numbers and return the result. Print the result with only 2 decimal places in
the main function.
Hint: See how to do it (click here!)
Problem 11
Ask the user for a message. Write a function to return the message in upper
case. Print the result.
Problem 12
In this problem, we will convert the value that the user will give to us from
miles to kilometers. Ask the user for a number that represents the miles. Write a
function to return the kilometers that this number of miles represents. Print the
result.
Hint: 1 mile = 1.60934 kilometers
3
Python Problems – Functions, Variables
Solutions
Problem 1
def hello():
print("hello")
hello()
Problem 2
# demo is the function name
def demo(name, age):
# print value
print(name, age)
# call function
demo("Ben", 25)
Problem 3
def double(n):
return n*2
print(double(2))
print(double(4))
print(double(6))
4
Python Problems – Functions, Variables
Problem 4
def func(x,y):
sum = int(x) + int(y)
return sum
x= input("x: ")
y= input("y: ")
result = func(x,y)
print(result)
Problem 5
def func(x,y):
sum = float(x) + float(y)
return sum
x= input("x: ")
y= input("y: ")
result = func(x,y)
print(result)
Problem 6
def func(x,y):
result = int(x) - int(y)
return result
x= input("x: ")
y= input("y: ")
result = func(x,y)
print(result)
5
Python Problems – Functions, Variables
Problem 7
def func(x,y):
result = int(x) * int(y)
return result
x= input("x: ")
y= input("y: ")
result = funct(x,y)
print(result)
Problem 8
def func(x,y):
result = int(x) / int(y)
return result
x= input("x: ")
y= input("y: ")
result = func(x,y)
print(result)
Problem 9
def func(x,y):
result = int(x) / int(y)
return result
x= input("x: ")
y= input("y: ")
result = func(x,y)
print(round(result))
6
Python Problems – Functions, Variables
Problem 10
def func(x,y):
result = int(x) * int(y)
return result
x= input("x: ")
y= input("y: ")
result = func(x,y)
print(“{:.2f}”.format(result))
Problem 11
def uppercase(txt):
return txt.upper()
txt = input("Message: ")
print(uppercase(txt))
Problem 12
def convert(miles):
return miles * 1.60934
miles= input("Miles: ")
print(f”Kilometers: {convert(miles)}”)
7
Python Problems – Conditionals
Questions
Problem 1
Ask the user for two integer inputs and print which one of them is the largest.
Problem 2
Ask the user for two integer inputs. Print YES if they are equal, NO otherwise.
Problem 3
Ask the user for two integer inputs. Write a function to return the sum of the
two integers values but if two values are the same, then return triple their sum. Print
the result.
Problem 4
Ask the user for two integer inputs. Write a function to return True if one of
them is 30 or if their sum is 30. Print the result.
Problem 5
Ask the user for two integer inputs. Write a program to check if each integer
is in the range 100…200 inclusive.
Problem 6
Call a function with two integers. The function should check which number is
nearest to the value 100 among them. Return 0 if the two numbers are equal.
Problem 7
Write a function to check if two integers have the same last digit.
2
Python Problems – Conditionals
Problem 8
Write a function to compute the sum of two integers. However, if the sum is in
the range 10…20 inclusive return 30.
Problem 9
Write a function that accepts two integers and return True if either one is 5 or
their sum or difference is 5.
Problem 10
Create an integer and store it in a variable. Print if the integer is even or odd.
Problem 11
Create a string. Print the first letter.
Problem 12
Create a string. Print the last letter.
Problem 13
Create a string. Print the string without the first letter.
Problem 14
Create a string. Print the string without the last letter.
Problem 15
Create a string with the value apple. Print ppl.
3
Python Problems – Conditionals
Problem 16
Create a string with the value “apple banana”. Split the string into two
variables (fruits). Print them.
Hint: check the split() method (click here!)
Problem 17
Create a string with the value “apple,banana”. Split the string into two
variables (fruits). Print them.
Hint: check the split() method (click here!)
Problem 18
Ask the user for a word. If the word contains the letter “a”, print “There is letter
a”. Otherwise, print “There is not letter a”.
Hint: check the in operator (click here!)
Problem 19
Ask the user for a word. If the word contains the letter “a” (it can be in lower
or upper case), print “There is letter a”. Otherwise, print “There is not letter a”.
Hint: check the in operator (click here!)
Problem 20
Ask the user for a message. If the message contains the word “hello” (it can
be in lower or upper case), print “Hello you”. Otherwise, print “No hello”.
Hint: check the in operator (click here!)
4
Python Problems – Conditionals
Solutions
Problem 1
# Prompt user for x
x = int(input("x: "))
# Prompt user for y
y = int(input ("y: "))
if x < y:
print("x is less than y")
elif x > y:
print("x is greater than y")
else:
print("x is equal to y")
Problem 2
# Prompt user for x
x = int(input("x: "))
# Prompt user for y
y = int(input ("y: "))
if x == y:
print("YES")
else:
print("NO")
5
Python Problems – Conditionals
Problem 3
#Definition of function
def check_nums(x,y):
if x == y:
return (x+y)*3
else:
return x+y
# Prompt user for x
x = int(input("x: "))
# Prompt user for y
y = int(input ("y: "))
#Call the function
print(check_nums(x,y))
Problem 4
#Definition of function
def check_nums(x,y):
if x == 30 or y == 30 or x+y == 30:
return True
return False
# Prompt user for x
x = int(input("x: "))
# Prompt user for y
y = int(input ("y: "))
#Call the function
print(check_nums(x,y))
6
Python Problems – Conditionals
Problem 5
#Definition of function
def check_nums(x,y):
if (x >= 100 and x <= 200) or (y >= 100 and y <= 200):
return True
return False
# Prompt user for x, y
x = int(input("x: "))
y = int(input ("y: "))
#Call the function
print(check_nums(x,y))
Problem 6
def get_nearest(x,y):
val = abs(x - 100)
val2 = abs(y - 100)
if val < val2:
return x
elif val > val2:
return y
else:
return 0
# Prompt user for x, y
x = int(input("x: "))
y = int(input ("y: "))
print(get_nearest(x,y))
7
Python Problems – Conditionals
Problem 7
def last_digit(x,y):
return abs(x % 10) == abs(y % 10)
# Prompt user for x
x = int(input("x: "))
y = int(input ("y: "))
# Call the function
print(last_digit(x,y))
Problem 8
def test(x,y):
sum = x + y
if sum >= 10 and sum <= 20:
return 30
else:
return sum
# Prompt user for y
x = int(input("x: "))
# Prompt user for y
y = int(input ("y: "))
# Call the function
print(test(x,y))
8
Python Problems – Conditionals
Problem 9
def test(x,y):
sum = x + y
diff = abs(x - y)
if sum ==5 or diff == 5 or x == 5 or y ==5:
return True
return False
# Prompt user for y
x = int(input("x: "))
# Prompt user for y
y = int(input ("y: "))
print(test(x,y))
Problem 10
num = 21
if num % 2 == 0:
print("even")
else:
print("odd")
Problem 11
text = "coding"
print(text[0])
9
Python Problems – Conditionals
Problem 12
text = "codingasdasdasdasda"
print(text[len(text)-1])
Problem 13
text = "coding"
print(text[1:])
Problem 14
text = "coding"
print(text[0:len(text)-1])
Problem 15
text = "apple"
print(text[1:4])
Problem 16
text = "apple banana"
print(text.split())
Problem 17
text = "apple,banana"
print(text.split(“,”))
10
Python Problems – Conditionals
Problem 18
word = input(“Word: “)
if “a” in word:
print(“There is letter a”)
else:
print(“There is not letter a”)
Problem 19
word = input(“Word: “)
if “a” in word.lower():
print(“There is letter a”)
else:
print(“There is not letter a”)
Problem 20
message = input(“Message: “)
if “hello” in message.lower():
print(“Hello you”)
else:
print(“No hello”)
11
Python Problems - Loops
Questions
Problem 1
Print the values from 1 to 100 using a for loop.
Problem 2
Print from 0 to 100, printing only the even numbers. Use a for loop.
Problem 3
Sum numbers from 1 to 100. Print the result. (The result is 5050).
Problem 4
Add 1 + 3 + 5 + … + 99. Print the result.
Problem 5
Loop from 100 to 1. Print the values. Use a for loop. (The result is 2500)
Problem 6
Add all the numbers from 99 + 97 + 95 + … + 1. Use a for loop.(The result is 2500)
Problem 7
Print numbers from 100 to 0 (backwards) using a for loop.
Problem 8
Print numbers from 1 to 100 using a while loop.
2
Python Problems - Loops
Problem 9
Print the following sequence of numbers: 0, 2, 4, 6 .... 98, 100 using a while
loop.
Problem 10
Print numbers from 100 to 0 (backward) using a while loop.
Problem 11
Create a function that prints hello as many times as you want (with an input).
Call this function with the number of times you want to print hello.
Problem 12
Create a function that returns double the input. Call the function multiple
times with different values. Print the result of each function call.
Problem 13
Print “cough” 3 times in 3 ways:
1. Using 3 print statements
2. Using a loop
3. Using a function
Problem 14
Ask the user for an integer input which will be stored in a variable called
“change”. Use a while loop to determine how many quarters will be given as “change”.
Example: 76 as change uses 3 quarters. 29 as change uses 1 quarter.
Problem 15
Keep asking a user for a positive value. This loop should break (look up the
break keyword in W3Schools) when the user input is positive. Keep looping until the
user inputs a positive value.
3
Python Problems - Loops
Problem 16
Loop through values from 1 to 100 inclusive. Check the conditions:
1.
2.
3.
4.
If the current number is divisible by 3, print Fizz.
If the current number is divisible by 5, print Buzz.
If the current number is divisible by both 3 and 5, print FizzBuzz.
Else, print the number.
Problem 17
Create a long string. Print two letters at a time with overlapping letters.
Example: “apple” should print:
“ap”
“pp”
“pl”
“le”
Problem 18
Create a long string. Print two letters at a time, without overlapping letters.
“appleb” should become:
“ap”
“pl”
“eb”
Problem 19
Create a string. Print three letters at a time.
Problem 20
Create two strings. Concatenate the second to the first.
4
Python Problems - Loops
Problem 21
Add numbers from 1 to 100 using a while loop. Print the result (Should give you
5050).
Problem 22
Create an integer. Count the number of digits.
Problem 23
Create a long number. Print the first two digits.
Problem 24
Create the following pattern:
*
**
***
****
Problem 25
Write a code to make the following pattern (using nested for loops):
1
22
333
4444
5
Python Problems - Loops
Problem 26
Write a code to make the following pattern (using nested for loops):
1
23
456
7 8 9 10
Problem 27
Ask users for an integer. Call a function that sums the digits in this integer.
Print the result.
Problem 28
Create a function that sums every other digit.
Problem 29
Ask user for a character. If the character is a letter in upper case, print
“True”. Otherwise, print “False”.
Hint: check the isupper() method (click here!)
6
Python Problems - Loops
Solutions
Problem 1
for i in range(1, 101):
print(i)
Problem 2
for i in range(0, 101, 2):
print(i)
Problem 3
sum = 0
for i in range(1, 11):
sum = sum + i
print(sum)
Problem 4
sum = 0
for i in range(1, 100, 2):
sum += i
print(sum)
Problem 5
for i in range(100, 0, -1):
print(i)
7
Python Problems - Loops
Problem 6
sum = 0
for i in range(99, 0, -2):
sum += i
print(sum)
Problem 7
for i in range(100,-1,-1):
print(i)
Problem 8
i =1
while (i <= 100):
print(i)
i += 1
Problem 9
i =0
while (i <= 100):
print(i)
i += 2
Problem 10
i = 100
while (i >= 0):
print(i)
i -= 1
8
Python Problems - Loops
Problem 11
def hello(n):
for i in range(n):
print("hello")
hello(5)
Problem 12
def double(n):
return n*2
print(double(2))
print(double(4))
print(double(6))
Problem 13
#Using 3 print statements
print("cough")
print("cough")
print("cough")
#Using a loop
for i in range(3):
print("cough")
#Using a function
def cough(n):
for i in range(n):
print("cough")
cough(3)
9
Python Problems - Loops
Problem 14
x = input("x: ")
count_quarters = 0
while (float(x) >= 25):
x -= 25
count_quarters += 1
print(count_quarters)
Problem 15
while True:
x = input("x: ")
if int(x) >= 0:
break
Problem 16
for i in range(1, 101):
if (i % 3 == 0 and i % 5 == 0):
print("FIZZBUZZ")
elif (i % 3 == 0):
print("FIZZ")
elif (i % 5 == 0):
print("BUZZ")
else:
print(i)
Problem 17
text = "applebanana"
10
Python Problems - Loops
for i in range(0, len(text)-1):
print(text[i:i+2])
Problem 18
text = "applefab"
for i in range(0, len(text)-1, 2):
print(text[i:i+2])
Problem 19
text = "applebananas"
for i in range(0, len(text)-1, 3):
print(text[i:i+3])
Problem 20
text1 = "banana"
text2 = "apple"
#text1 = text1 + text2
text1 += text2
print(text1)
11
Python Problems - Loops
Problem 21
counter = 0
sum = 0
while (counter <= 100):
sum+= counter
counter += 1
print(sum)
Problem 22
num = 231231231
counter = 0
while num > 0:
num = num // 10
counter += 1
print(counter)
Problem 23
num = 23423323
print(num // pow(10, 6))
Problem 24
# Prompt user for number of rows
num_rows = input("Number of rows: ")
for row in range(1, int(num_rows)):
for col in range(1, row+1):
print("*", end="")
print()
12
Python Problems - Loops
Problem 25
num_rows = input("Number of rows: ")
for row in range(1, int(num_rows)):
for col in range(1, row+1):
print(row, end="")
print()
Problem 26
num_rows = input("Number of rows: ")
k=1
for row in range(1, int(num_rows)):
for col in range(1, row+1):
print(k, end="")
k += 1
print()
Problem 27
def get_sum_digits(x):
sum = 0
while(x != 0):
sum += x % 10
x //= 10
return sum
x = input("x: ")
print(get_sum_digits(int(x)))
13
Python Problems - Loops
Problem 28
def get_sum_digits(x):
sum = 0
isAlternateDigit = False
while(x != 0):
if isAlternateDigit:
sum += x % 10
isAlternateDigit = not isAlternateDigit
x //= 10
return sum
# Prompt user for x
x = input("x: ")
print(get_sum_digits(int(x)))
Problem 29
char = input(“Character: “)
if char.isupper():
print(True)
else:
print(False)
14
Python Problems - Loops
Questions
Problem 1
Create a list. Loop through the list using:
For
each
loop
(similar
to
the
first
https://www.w3schools.com/python/python_for_loops.asp).
example
in:
For loop printing the index of the list (use the range function)
For loop printing the value using the index (use the range function)
Problem 2
Create an empty list. Append a number to this list. Print the list.
Problem 3
Create a list. Append values 1 to 100 to this list. Print the final list.
Problem 4
Create a list. Append values 1, 3, 5, … + 99 to list.
Problem 5
Create a list of strings (with more than 4 letters). Print the 3rd letter of the
2nd string.
Problem 6
Create a list with multiple numbers. Print the number in reverse order using
a loop.
Problem 7
Create a list called even. Create another list called odd. Loop through the
values from 1 to 100. If the number is even, add it to the even list. If the number is odd,
add it to the odd list.
2
Python Problems - Loops
Problem 8
Create and print a dictionary.
Problem 9
Create a dictionary. Print its keys and values without a loop.
Problem 10
Create a dictionary. Loop over its keys and values using the .items() function.
Problem 11
Create a dictionary. Print the value of a particular key.
Problem 12
Create a dictionary. Add a key and value to the dictionary. Print the result.
Problem 13
Create a list of strings that contains the name Rodrigo. Check if Rodrigo is in
the list. If he is, print Found, otherwise Not Found. Use the function in.
Problem 14
Create a dictionary with names and phone numbers. Ask user for a name. If
name in the dictionary, print their phone number.
Problem 15
Create a list of dictionaries. Print it.
3
Python Problems - Loops
Problem 16
Create a dictionary where the keys are numbers between 1 and 15 (both
included) and the values are square of keys. Print the dictionary.
Problem 17
Create a dictionary. Loop through the dictionary (using a for loop). Print the
keys.
Problem 18
Create a dictionary. Loop through the dictionary (using a for loop). Print the
values.
4
Python Problems - Loops
Solutions
Problem 1
x = [10, 9, 5, 3, 2]
#for each loop
for val in x:
print(val)
#loop through the list index
for i in range(len(x)):
print(i)
#loop through the values of the list, using the index
for i in range(len(x)):
print(x[i])
Problem 2
x = []
x.append(10)
print(x)
Problem 3
x = []
for i in range(1, 101):
x.append(i)
print(x)
5
Python Problems - Loops
Problem 4
x = []
for i in range(1, 100, 2):
x.append(i)
sum = 0
for val in x:
sum += val
print(sum)
Problem 5
x = ["apple", "banana", "watermellon", "lemon"]
print(x[1][2])
Problem 6
x = [9, 3, 5, 3, 2, 1, 0]
for i in range(len(x)-1, -1, -1):
print(x[i])
6
Python Problems - Loops
Problem 7
even = []
odd = []
for i in range(1, 10):
if i % 2 == 0:
even.append(i)
else:
odd.append(i)
print(even)
print(odd)
Problem 8
thisdict = {
"brand": "Ford",
"model": "Mustang",
"year": 1964
}
print(thisdict)
Problem 9
car = {
"brand": "Ford",
"model": "Mustang",
"year": 1964
}
print(car.values())
print(car.keys())
7
Python Problems - Loops
Problem 10
thisdict = {
"brand": "Ford",
"model": "Mustang",
"year": 1964
}
for x, y in thisdict.items():
print(x, y)
Problem 11
thisdict = {
"brand": "Ford",
"model": "Mustang",
"year": 1964
}
print(thisdict["model"])
print(thisdict["year"])
Problem 12
thisdict = {
"brand": "Ford",
"model": "Mustang",
"year": 1964
}
thisdict["color"] = "red"
print(thisdict)
8
Python Problems - Loops
Problem 13
names = ["Bill", "Charlie", "Fred", "George", "Ginny", "Percy", "Rodrigo"]
if "Rodrigo" in names:
print("Found")
else:
print("Not found")
Problem 14
people = {
"Brian": "+1-617-495-1000",
"David": "+1-949-468-2750"
}
name = input("Name: ")
if name in people:
print(f"Number: {people[name]}")
Problem 15
person1 = {
"name": "Rodrigo",
"age": 28
}
person2 = {
"name": "Giovanna",
"age": 22
}
l = [person1, person2]
print(l)
9
Python Problems - Loops
Problem 16
d=dict()
for x in range(1,16):
d[x]=x**2
print(d)
Problem 17
thisdict = {
"brand": "Ford",
"model": "Mustang",
"year": 1964
}
for key in thisdict:
print(key)
Problem 18
thisdict = {
"brand": "Ford",
"model": "Mustang",
"year": 1964
}
for key in thisdict:
print(thisdict[key])
10
Python Problems - Exceptions
Questions
Problem 1
Ask the user for a number. If the user does not type in a number, prompt the
user again. If the user gives a number, calculate the double.
Problem 2
Ask the user for a number. Multiply the number by 5. If the user does not give
you a number, prompt the user again.
Problem 3
Ask the user for two numbers separated by a comma. If the user does not type
in the correct format, prompt the user again. If the user gives two numbers separated
by a comma, get the two numbers, and calculate their sum.
Problem 4
Create a list (for example fruits = [“apple”, “banana”, “orange”]). Ask the user
for a fruit. If the user does not type in a fruit that exists in the list, prompt the user
again. If the user gives an existing fruit, print “We have this fruit!”.
Problem 5
Create a dictionary (for example fruits = {“apple”:1 , “banana”: 3, “orange”: 2}).
Ask the user for a fruit. If the user does not type in a fruit that exists in the dictionary,
prompt the user again. If the user gives an existing fruit, print the quantity of this fruit
(the value of the fruit in the dictionary).
2
Python Problems - Exceptions
Solutions
Problem 1
while True:
number = input("Number: ")
try:
double = int(number) * 2
print(double)
break
except:
pass
Problem 2
while True:
number = input("Number: ")
try:
result = int(number) * 5
print(result)
break
except:
pass
3
Python Problems - Exceptions
Problem 3
while True:
numbers = input("Numbers: ")
try:
number1, number2 = numbers.split(“,”)
result = int(number1) + int(number1)
print(result)
break
except:
pass
Problem 4
fruits = ["apple", "banana", "orange"]
while True:
fruit = input("fruit: ")
try:
if fruit in fruits:
print("We have this fruit!")
break
except:
pass
4
Python Problems - Exceptions
Problem 5
fruits = {"apple":1 , "banana": 3, "orange": 2}
while True:
fruit = input("fruit: ")
try:
if fruit in fruits:
print(fruits[fruit])
break
except:
pass
5
Python Problems - Libraries
Questions
Problem 1
Ask the user for two integers. Write a Python program to generate a random
number between two of these integers (inclusive). Use random.randint() (click here!)
Problem 2
Create a list with 3 elements. Write a Python program to print a random
element from this list. Use random.choice() (click here!)
Problem 3
Ask the user for one integer. Calculate the square root of that number. Use
the math.sqrt() (click here!)
Problem 4
Call the program from the terminal with arguments. Print the arguments.
Problem 5
Call the program from the terminal with arguments. Print “Hello, world” if
there are arguments. Else, print “Hello” with the value of the argument.
Problem 6
Call the program from the terminal with one number as an argument. If there
are no arguments, print “Missing command-line argument”. If the argument is not a
number, print “Command-line argument is not a number”. If the command-line
argument is a number, print the double of it.
2
Python Problems - Libraries
Solutions
Problem 1
import random
x = input("x: ")
y = input("y: ")
random_number = random.randint(int(x), int(y))
print(random_number)
Problem 2
import random
fruits = ["apple", "banana", "orange"]
random_element = random.choice(fruits)
print(random_element)
Problem 3
import math
number = input("Number: ")
root = math.sqrt(int(number))
print(root)
3
Python Problems - Libraries
Problem 4
from sys import argv
for arg in argv:
print(arg)
print(len(argv))
Problem 5
from sys import argv
if len(argv) == 2:
print(f"hello, {argv[1]}")
else:
print("hello, world")
Problem 6
import sys
if len(sys.argv) != 2:
sys.exit("Missing command-line argument")
try:
double = int(sys.argv[1]) * 2
print(double)
except:
sys.exit("Command-line argument is not a number")
4
Python Problems – Conditionals
Questions
Problem 1
Create a function that returns double the input. Then, create a new file with
“test_” in the beginning of the name of the file. Test the function.
Problem 2
Ask user for two integers in the main function. Create a function that sum
them and return the result. Then, create a new file with “test_” in the beginning of the
name of the file. Test the function.
Problem 3
Ask user for two float numbers in the main function. Create a function that
sum them and return the result. Then, create a new file with “test_” in the beginning
of the name of the file. Test the function.
Problem 4
Ask user for two integers in the main function. Create a function that subtract
them and return the result. Then, create a new file with “test_” in the beginning of the
name of the file. Test the function.
Problem 5
Ask user for two integers in the main function. Create a function that multiply
them and return the result. Then, create a new file with “test_” in the beginning of the
name of the file. Test the function.
Problem 6
Ask user for two integers in the main function. Create a function that divides
the two integers and return the result. Then, create a new file with “test_” in the
beginning of the name of the file. Test the function.
2
Python Problems – Conditionals
Problem 7
In this problem, we will convert the value that the user will give to us from
miles to kilometers. Ask the user for a number that represents the miles. Write a
function to return the kilometers that this number of miles represents. Then, create
a new file with “test_” in the beginning of the name of the file. Test the function.
Hint: 1 mile = 1.60934 kilometers
Problem 8
Ask users for an integer. Call a function that sums the digits in this integer.
Then, create a new file with “test_” in the beginning of the name of the file. Test the
function.
Problem 9
Create a function that sums every other digit. Then, create a new file with
“test_” in the beginning of the name of the file. Test the function.
3
Python Problems – Conditionals
Solutions
Problem 1
problem1.py
def double(n):
return n*2
test_problem1.py
from problem1 import double
def test_double():
assert double(2) == 4
assert double(3) == 6
Problem 2
problem2.py
def func(x,y):
sum = int(x) + int(y)
return sum
test_problem2.py
from problem2 import func
def test_func():
assert func(2,3) == 5
assert func(10,100) == 110
4
Python Problems – Conditionals
Problem 3
problem3.py
def func(x,y):
sum = float(x) + float(y)
return sum
test_problem3.py
from problem3 import func
def test_func():
assert func(2.3,5) == 7.3
assert func(10.7,9.3) == 20.0
Problem 4
problem4.py
def func(x,y):
result = int(x) - int(y)
return result
test_problem4.py
from problem4 import func
def test_func():
assert func(5,3) == 2
assert func(10,20) == -10
5
Python Problems – Conditionals
Problem 5
problem5.py
def func(x,y):
result = int(x) * int(y)
return result
test_problem5.py
from problem5 import func
def test_func():
assert func(5,3) == 15
assert func(10,20) == 200
Problem 6
problem6.py
def func(x,y):
result = int(x) / int(y)
return result
test_problem6.py
from problem6 import func
def test_func():
assert func(10,2) == 5
assert func(20,10) == 2
6
Python Problems – Conditionals
Problem 7
problem7.py
def convert(miles):
return miles * 1.60934
test_problem7.py
from problem7 import convert
def test_convert():
assert convert(10) == 16.0934
assert convert(2) == 3.21868
Problem 8
problem8.py
def get_sum_digits(x):
sum = 0
while(x != 0):
sum += x % 10
x //= 10
return sum
test_problem8.py
from problem8 import get_sum_digits
def test_get_sum_digits():
assert get_sum_digits(12345) == 15
assert get_sum_digits(445566) == 30
7
Python Problems – Conditionals
Problem 9
problem9.py
def get_sum_digits(x):
sum = 0
isAlternateDigit = False
while(x != 0):
if isAlternateDigit:
sum += x % 10
isAlternateDigit = not isAlternateDigit
x //= 10
return sum
test_problem9.py
from problem9 import get_sum_digits
def test_get_sum_digits():
assert get_sum_digits(12345) == 6
assert get_sum_digits(445566) == 15
8
Python Problems – File I/O
Questions
Problem 1
Create a file called days.txt with days of the week, one at each line. Open the
file and read its content.
days.txt file:
January
Problem 2
Create a file called days.txt with days of the week, one at each line. Open the
file and read the first line.
days.txt file:
January
Problem 3
Create a file called numbers.txt. Write numbers 1 to 100, at each line.
Example of numbers.txt file:
1
2
3
...
99
100
2
Python Problems – File I/O
Problem 4
Open the file numbers.txt and read the first line. Use with open() as syntax.
Problem 5
Create a spreadsheet file and put 10 of your favorite desserts in the first
column. Download file with .csv extension. Open CSV file. Print the elements of the
file.
Example of desserts.csv file:
cheesecake
cookie
ice-cream
...
tiramisu
chocolate
Problem 6
Create a spreadsheet file and put 10 of your favorite desserts in the first
column (with some repetitive ones). Download file with .csv extension. Open CSV file.
Count the number of desserts, put result in a dictionary and print it.
Problem 7
Create a spreadsheet file and put 10 of your favorite desserts in the first
column (with some repetitive ones). In the first row of the column put the title of the
column as dessert. Download file with .csv extension. Open CSV file. Print each
dessert using the name of the column.
3
Python Problems – File I/O
Solutions
Problem 1
days_file = open('days.txt','r')
print(days_file.read())
days_file.close()
Problem 2
days_file = open('days.txt','r')
print(days_file.readline(), end="")
days_file.close()
Problem 3
num_files = open('numbers.txt','w')
for i in range(1, 101):
num_files.write(f"{str(i)}\n")
num_files.close()
Problem 4
with open("numbers.txt", "r") as file:
print(file.readline())
4
Python Problems – File I/O
Problem 5
import csv
with open("desserts.csv", "r") as file:
reader = csv.reader(file)
for row in reader:
print(row[0])
Problem 6
import csv
desserts_count = dict()
with open("desserts.csv", "r") as file:
reader = csv.reader(file)
for row in reader:
current_dessert = row[0]
if current_dessert in desserts_count:
desserts_count[current_dessert] += 1
else:
desserts_count[current_dessert] = 1
print(desserts_count)
5
Python Problems – File I/O
Problem 7
import csv
desserts_count = dict()
with open("desserts.csv", "r") as file:
reader = csv.DictReader(file)
for row in reader:
print(row['dessert'])
6
Python Problems – Regular Expressions
Questions
Problem 1
Write a Python program to check that a string contains only a certain set of
characters (in this case a-z, A-Z and 0-9).
Problem 2
Write a Python program that matches a string that has an a followed by zero
or more b's.
Problem 3
Write a Python program that matches a string that has an a followed by one
or more b's.
Problem 4
Write a Python program that matches a string that has an a followed by three
'b'.
Problem 5
Write a Python program that matches a string that has an a followed by two
to three 'b'.
Problem 6
Write a Python program to find sequences of lowercase letters joined with a
underscore.
Problem 7
Write a Python program that matches a word at the beginning of a string.
2
Python Problems – Regular Expressions
Problem 8
Write a Python program that matches a word containing 'z'.
Problem 9
Write a Python program to search some literals strings in a string. Go to the
editor Sample text : 'The quick brown fox jumps over the lazy dog.' Searched words :
'fox', 'dog', 'horse'.
Problem 10
Write a Python program to find the substrings within a string.
Sample text :
'Python exercises, PHP exercises, C# exercises'
Pattern :
'exercises'
Note: There are two instances of exercises in the input string.
Problem 11
Write a Python program to extract year, month, and date from an URL.
Problem 12
Write a Python program to find all words starting with 'a' or 'e' in each string.
3
Python Problems – Regular Expressions
Solutions
Problem 1
import re
def is_allowed_specific_char(string):
s = re.search(r'[^a-zA-Z0-9.]', string)
return not bool(s)
print(is_allowed_specific_char("ABCDEFabcdef123450"))
print(is_allowed_specific_char("*&%@#!}{"))
Problem 2
import re
def text_match(text):
if re.search(r'ab*?', text):
return 'Found a match!'
else:
return('Not matched!')
print(text_match("ac"))
print(text_match("abc"))
print(text_match("abbc"))
4
Python Problems – Regular Expressions
Problem 3
import re
def text_match(text):
if re.search(r'ab+?', text):
return 'Found a match!'
else:
return('Not matched!')
print(text_match("ac"))
print(text_match("abc"))
print(text_match("abbc"))
Problem 4
import re
def text_match(text):
if re.search(r'ab{3}?', text):
return 'Found a match!'
else:
return('Not matched!')
print(text_match("abbb"))
print(text_match("aabbbbbc"))
5
Python Problems – Regular Expressions
Problem 5
import re
def text_match(text):
if re.search(r'ab{2,3}?', text):
return 'Found a match!'
else:
return('Not matched!')
print(text_match("abbb"))
print(text_match("aabbbbbc"))
Problem 6
import re
def text_match(text):
if re.search(r' ^[a-z]+_[a-z]+$', text):
return 'Found a match!'
else:
return('Not matched!')
print(text_match("aab_cbbbc"))
print(text_match("aab_Abbbc"))
print(text_match("Aaab_abbbc"))
6
Python Problems – Regular Expressions
Problem 7
import re
def text_match(text):
if re.search(r' ^\W+', text):
return 'Found a match!'
else:
return('Not matched!')
print(text_match("The quick brown fox jumps over the lazy dog."))
print(text_match(" The quick brown fox jumps over the lazy dog."))
Problem 8
import re
def text_match(text):
if re.search(r' ^\w*z.\w*', text):
return 'Found a match!'
else:
return('Not matched!')
print(text_match("The quick brown fox jumps over the lazy dog."))
print(text_match("Python Exercises."))
7
Python Problems – Regular Expressions
Problem 9
import re
patterns = [ 'fox', 'dog', 'horse' ]
text = 'The quick brown fox jumps over the lazy dog.'
for pattern in patterns:
print('Searching for "%s" in "%s" ->' % (pattern, text),)
if re.search(pattern, text):
print('Matched!')
else:
print('Not Matched!')
Problem 10
import re
text = 'Python exercises, PHP exercises, C# exercises'
pattern = 'exercises'
for match in re.findall(pattern, text):
print('Found "%s"' % match)
8
Python Problems – Regular Expressions
Problem 11
import re
def extract_date(url):
return re.findall(r'/(\d{4})/(\d{1,2})/(\d{1,2})/', url)
url1= "https://www.washingtonpost.com/news/football-insider/wp/2016/09/02/odellbeckhams-fame-rests-on-one-stupid-little-ball-josh-norman-tells-author/"
print(extract_date(url1))
Problem 12
import re
# Input.
text = "The following example creates an ArrayList with a capacity of 50 elements.
Four elements are then added to the ArrayList and the ArrayList is trimmed
accordingly."
#find all the words starting with 'a' or 'e'
list = re.findall("[ae]\w+", text)
# Print result.
print(list)
9
Python Problems – Regular Expressions
Questions
Problem 1
Write a Python program to create a Vehicle class with max_speed and mileage
instance attributes.
Problem 2
Create a child class Bus that will inherit all of the variables and methods of
the Vehicle class (Vehicle class create on Problem 1).
Problem 3
Create a Bus class that inherits from the Vehicle class. Give the capacity
argument of Bus.seating_capacity() a default value of 50.
Hint: The Vehicle class is the following:
class Vehicle:
def __init__(self, name, max_speed, mileage):
self.name = name
self.max_speed = max_speed
self.mileage = mileage
def seating_capacity(self, capacity):
return f"The seating capacity of a {self.name} is {capacity} passengers"
2
Python Problems – Regular Expressions
Problem 4
Define a class attribute”color” with a default value white. I.e., Every Vehicle
should be white.
Use the following code for this exercise.
class Vehicle:
def __init__(self, name, max_speed, mileage):
self.name = name
self.max_speed = max_speed
self.mileage = mileage
class Bus(Vehicle):
pass
class Car(Vehicle):
pass
Problem 5
Create a Bus child class that inherits from the Vehicle class. The default fare
charge of any vehicle is seating capacity * 100. If Vehicle is Bus instance, we need to
add an extra 10% on full fare as a maintenance charge. So total fare for bus instance
will become the final amount = total fare + 10% of the total fare.
Note: The bus seating capacity is 50. so the final fare amount should be 5500. You
need to override the fare() method of a Vehicle class in Bus class.
Use the following code for your parent Vehicle class. We need to access the parent
class from inside a method of a child class.
3
Python Problems – Regular Expressions
class Vehicle:
def __init__(self, name, mileage, capacity):
self.name = name
self.mileage = mileage
self.capacity = capacity
def fare(self):
return self.capacity * 100
class Bus(Vehicle):
pass
School_bus = Bus("School Volvo", 12, 50)
print("Total Bus fare is:", School_bus.fare())
4
Python Problems – Regular Expressions
Solutions
Problem 1
class Vehicle:
def __init__(self, max_speed, mileage):
self.max_speed = max_speed
self.mileage = mileage
modelX = Vehicle(240, 18)
print(modelX.max_speed, modelX.mileage)
Problem 2
class Vehicle:
def __init__(self, name, max_speed, mileage):
self.name = name
self.max_speed = max_speed
self.mileage = mileage
class Bus(Vehicle):
pass
School_bus = Bus("School Volvo", 180, 12)
print("Vehicle Name:", School_bus.name,
"Mileage:", School_bus.mileage)
"Speed:",
School_bus.max_speed,
5
Python Problems – Regular Expressions
Problem 3
class Vehicle:
def __init__(self, name, max_speed, mileage):
self.name = name
self.max_speed = max_speed
self.mileage = mileage
def seating_capacity(self, capacity):
return f"The seating capacity of a {self.name} is {capacity} passengers"
class Bus(Vehicle):
# assign default value to capacity
def seating_capacity(self, capacity=50):
return super().seating_capacity(capacity=50)
School_bus = Bus("School Volvo", 180, 12)
print(School_bus.seating_capacity())
6
Python Problems – Regular Expressions
Problem 4
class Vehicle:
# Class attribute
color = "White"
def __init__(self, name, max_speed, mileage):
self.name = name
self.max_speed = max_speed
self.mileage = mileage
class Bus(Vehicle):
pass
class Car(Vehicle):
pass
School_bus = Bus("School Volvo", 180, 12)
print(School_bus.color, School_bus.name,
"Mileage:", School_bus.mileage)
"Speed:",
School_bus.max_speed,
car = Car("Audi Q5", 240, 18)
print(car.color, car.name, "Speed:", car.max_speed, "Mileage:", car.mileage)
7
Python Problems – Regular Expressions
Problem 5
class Vehicle:
def __init__(self, name, mileage, capacity):
self.name = name
self.mileage = mileage
self.capacity = capacity
def fare(self):
amount = super().fare()
amount += amount * 10 / 100
return amount
class Bus(Vehicle):
pass
School_bus = Bus("School Volvo", 12, 50)
print("Total Bus fare is:", School_bus.fare())
8
DOR'S
CODING
SCHOOL
Learn To Program Workbook
EBOOK
Syllabus
2
Syllabus
Topic
Weeks
1
Scratch
2
3
4
5
C Language
6
7
Arrays
8
9
Algorithms
10
11
Memory
12
13
Data
Structure
14
15
Python
16
17
Content
Watch Scratch lecture (Lecture 0 video)
Watch Dor’s Coding School Scratch Intro video
Do MIT PDFs
Watch Soccer Tips video
Start Soccer Project
Finish Soccer Project
Watch our solution.
Watch C lecture (Lecture 1 video)
Watch Dor's Coding School C problems
Finish Dor's C problems (each problem under 3 minutes)
Finish Lab 1
Finish Cash
Finish Mario
Finish Credit (if more advanced)
Watch Arrays lecture (Lecture 2 video)
Watch Dor’s Array Video (each problem under 4 minutes)
Finish Lab 2
Finish Runoff
Finish Caesar or Substitution (if more comfortable)
Watch Algorithms lecture (Lecture 3 video)
Watch Dor’s Algorithms video
Finish Lab 3
Finish Plurality
Finish Runoff
Watch Memory lecture (Lecture 4 video)
Watch Dor’s Memory Video (each problem under 4 minutes)
Finish Lab 4
Finish Filter
Finish Recover
Watch Data Structure lecture (Lecture 5 video)
Watch Dor’s Memory Video (each problem under 5 minutes)
Start Speller
Watch Python Lecture (Lecture 6 video)
Watch Scratch to Python Dor’s Videos (each problem under
2 min)
Do Warmup1 and String1 on CodingBat
Finish Hello and Mario
Do Warmup1 and String1 on CodingBat
Finish Hello and Mario
Syllabus
18
19
Python
20
21
22
23
24
SQL
25
26
27
28
Flask
29
30
31
32
HTML, CSS
33
34
Python
35
36
Django
37
SQL, Models
and
Migrations
38
39
40
3
Do Logic1 and List1 on CodingBat
Finish Cash
Do Warmup2 and String2 on CodingBat
Finish Credit
Finish Readability
Do all CodingBat problems (except for List 2 and Logic 2) in
under 90 minutes.
Watch Python Advanced Videos. Do all problems under 4
minutes.
Finish Lab 6
Finish DNA
Watch SQL lecture
Do all SQL Bolt problems
Finish Lab 7
Finish Movies
Finish Fiftyville
Watch HTML, CSS and Javascript video
Watch Dor’s Video
Finish Lab 8
Finish Problem Set 8
Watch Flask Video
Watch Dor’s To Do Video
Finish Lab 9
Finish Finance
Start final project
Keep working on final project
Finish Final Project
Watch HTML/CSS Lecture
Sololearn Responsive Web Design
Sololearn HTML
Sololearn CSS
Watch Python Lecture
Start Search
Finish Search
Watch Django Lecture
Start Wiki
Watch Python Lecture
Finish Wiki
Watch SQL lecture
Start Commerce
Continue Commerce
Finish Commerce
Syllabus
41
JavaScript
42
43
React-Redux
44
45
46
Market
Yourself
47
48-53
4
Watch Javascript
Sololearn Javascript
Finish Javascript
Sololearn React/Redux
Watch and Do by yourself React To Do
Start Network
Continue Network
Finish Network
Watch course How To Market Yourself as a Self-Taught
Developer
Watch Git
Plan Final Project
Finish Final Project
Checklist – Soccer (Problem Set 0)
Problem Set 0 – Soccer Game
Requirements
• Your project must have at least two sprites, at least one of which must
resemble something other than a cat.
• Your project must have at least three scripts total (i.e., not necessarily three
per sprite).
• Your project must use at least one condition, one loop, and one variable.
• Your project must use at least one sound.
• Your project should be more complex than most of those demonstrated in
lecture (many of which, though instructive, were quite short) but it can be less
complex than Ivy’s Hardest Game. As such, your project should probably use
a few dozen puzzle pieces overall.
Welcome Page
Background color always changing
Since it is changing continuously, this is a forever loop. The only reason why
this loop ends is when you click to Start the game.
So, to make this background color always change you should use:
2
Checklist – Soccer (Problem Set 0)
Character moving/dancing
Since it is changing continuously, this is a forever loop. The property that is
always changing is the costume. If you look on Scratch, you will find 13 costumes to
this character.
So, to make this character always change position you should use:
Ball up and down
Since it is changing continuously, this is a forever loop. The only reason why
this loop ends is when you click to Start the game.
To make the ball go up and down use the ‘change by y’ block.
So, you should use something like this:
3
Checklist – Soccer (Problem Set 0)
At this point, the project that we created looks like this:
Game Page
How to Kick
You are going to use a Sensing block in the ball that is going to set where the
ball should go depending on each character that is close to it.
For example, if the key D is pressed and the character is Ben, the ball should
move 30 steps to the right.
This is going to be a forever loop. Look at the example below:
4
Checklist – Soccer (Problem Set 0)
How to score goal
Create a red line to go over the goal. The line is in the image below:
Make this line invisible by using the set ghost effect.
Use the forever loop to check if the ball touched the line. If they touched, the
goal was scored.
At this point, our project looks like this:
5
Checklist – Soccer (Problem Set 0)
End of the game
In the background you can create a forever loop to make the game working.
And you can create one if condition to set when this game is going to finish.
For example, after someone scores a goal, you can finish the game and switch
the background to another one, creating this way a Congratulations Page.
At this point, our project looks like this:
6
How To Use The Debug50
How To Use The Debug50
In CS50 IDE, you can use a powerful tool, developed by CS50’s staff, called
debug50 to help you to debug programs.
This debugger is a program that will run your code step-by-step and let you
look at variables and other information while your code is running.
How To Run The Debugger?
The first thing you have to do is adding a breakpoint, or indicator for a line of
code where the debugger should pause our program.
The image below has an example of what you should do if your code was
written in C Language:
2
How To Use The Debug50
The image below has an example of what you should do if your code was
written in Python:
To start the debug50, you have to run in your terminal the following command:
C language: make name_of_your_program
debug50 ./name_of_your_program
Python:
debug50 name_of_your_program.py
The example below we have a program in C Language and we are trying to
run it using the debug50. Check how you should do it:
The example below we have a program in Python and we are trying to run it
using the debug50. Check how you should do it:
3
How To Use The Debug50
If you forget to put a breakpoint in your code, the terminal will return you a
message explaining to do it, like we can see in the image below:
Tools In Debug50
1. Breakpoints: the debugger show to us the breakpoint that we put in the code.
You can check this by the green arrows in the image below.
4
How To Use The Debug50
2. Local variables: the debugger show to us the variables used in the code and
its type and current values. You can check this by the green arrows in the
image below.
3. Resume: it is the blue triangle pointed by the yellow arrow in the image below.
When you click in the button, the debug50 will run your code until it hits the
next breakpoint.
4. Step Over: it is the curved arrow pointed by the yellow arrow in the image
below. When you click this button the debug50 is going to skip over a block of
code. This is used, for example, when you use the strlen function from string.h
library in C Language.
5
How To Use The Debug50
5. Step Into: it is the down arrow pointed by the yellow arrow in the image below.
When you click in the button, the debug50 is going to move through your code
slowly one line at a time.
6. Step Out: it is the button pointed by the yellow arrow in the image below. When
you click on this button, the debug50 is going to run your code step out of a
function (other than main). This is one button that is rarely used.
6
How To Use The Debug50
7. Deactivate All Breakpoints: it is the circle pointed by the yellow arrow in the
image below. When you click this button, the debug50 clears all the breakpoint
that you set in your program.
7
31 Programming Fundamental Problems – C Language
Questions
Problem 1
Ask user for two integer inputs and print which one of them is the largest.
Problem 2
Print numbers from 1 to 100 in C using for loops.
Problem 3
Print the following sequence of number: 0 + 2 + 4 + 6 .... 98 + 100 using for
loops.
Problem 4
Print numbers from 100 to 0 (backwards) using for loops.
Problem 5
Print numbers from 1 to 100 using a while loop.
Problem 6
Print the following sequence of number: 0 + 2 + 4 + 6 .... 98 + 100 using while
loops.
Problem 7
Print numbers from 100 to 0 (backwards) using while loops.
Problem 8
Ask user for two integer inputs. Print YES if they are equal, NO otherwise.
2
31 Programming Fundamental Problems – C Language
Problem 9
Create a function that prints Hello.
Problem 10
Create a function that prints Hello as many times as you want.
Problem 11
Create a function that returns the double of a number. Call the function
multiple times. Print the result.
Problem 12
Print “cough” in 3 ways:
1. Using 3 printf statements
2. Using a loop
3. Using a function
Problem 13
Ask user for two integer inputs. Write a C function to return the sum of the
two given integer values but if two values are the same, then return triple their sum.
Print the result.
Problem 14
Ask user for two integer inputs. Write a C function to compute return True if
one of them is 30 or if their sum is 30. Print the result.
Problem 15
Sum the numbers from 1 to 10. Print the result.
3
31 Programming Fundamental Problems – C Language
Problem 16
Write a C program to check if two integers are in the range 100…200 inclusive.
Problem 17
Ask user for integer input. Print if input is even or odd. Note: use the
remainder.
Problem 18
Ask user for integer input which will be our “change”. Use a while loop to
determine how many quarters will be given as “change”. Example: 76 as changes
uses 3 quarters. 29 as change uses 1 quarter.
Problem 19
Create a function that keeps asking a user for a positive value. This function
should return the user input only if it is positive. Use do…while. Keep looping until
user inputs positive value. Return the number to main and print it.
Problem 20
Write a C program to check which number nearest to the value 100 among two
given integers. Return 0 if the two numbers are equal.
Problem 21
Write a C program to check if two given integers have the same last digit.
Problem 22
Write a C program to compute the sum of the two given integers. If the sum is
in the range 10…20 inclusive return 30.
4
31 Programming Fundamental Problems – C Language
Problem 23
Write a C program that accept two integers and return True if either one is 5
or their sum or difference is 5.
Problem 24
Loop through values from 1 to 50 inclusive. Check the conditions:
▪
▪
▪
▪
If the current number is divisible by 3, print Fizz.
If the current number is divisible by 5, print Buzz.
If the current number is divisible by both 3 and 5, print FizzBuzz.
Else, print the number.
Problem 25
Write a program in C to display the the following pattern using an asterisk.
The pattern will be :
*
**
***
****
Problem 26
Write a program in C to make such a pattern like right angle triangle with a
number which will repeat a number in a row. The pattern like:
1
22
333
4444
5
31 Programming Fundamental Problems – C Language
Problem 27
Write a program in C to make such a pattern like right angle triangle with a
number which will repeat a number in a row. The pattern like:
1
23
456
7 8 9 10
Problem 28
Create a C function to get how many digits a credit card has.
Problem 29
Ask user for an integer. Call a function that sums the digits in this integer.
Print the result.
Problem 30
Create a C function that sum every other digit.
Problem 31
Grab the fist two digits of 23032243 in two different ways.
6
31 Programming Fundamental Problems – C Language
Solutions
Problem 1
#include <cs50.h>
#include <stdio.h>
int main(void)
{
// Prompt user for x
int x = get_int("x: ");
// Prompt user for y
int y = get_int("y: ");
// Compare x and y
if (x < y)
{
printf("x is less than y\n");
}
else if (x > y)
{
printf("x is greater than y\n");
}
else
{
printf("x is equal to y\n");
}
}
7
31 Programming Fundamental Problems – C Language
Problem 2
#include <stdio.h>
int main(void)
{
for (int i = 0; i < 101; i++)
{
printf("%d\n", i);
}
}
Problem 3
#include <stdio.h>
int main(void)
{
for (int i = 0; i < 101; i+=2)
{
printf("%i\n", i);
}
}
8
31 Programming Fundamental Problems – C Language
Problem 4
#include <stdio.h>
int main(void)
{
for (int i = 100; i >= 0; i-=1)
{
printf("%i\n", i);
}
}
Problem 5
#include <stdio.h>
int main(void)
{
int counter = 0;
while (counter <= 100)
{
printf("%i\n", counter);
counter += 1;
}
}
9
31 Programming Fundamental Problems – C Language
Problem 6
#include <stdio.h>
int main(void)
{
int counter = 0;
while (counter <= 100)
{
printf("%i\n", counter);
counter += 2;
}
}
Problem 7
#include <stdio.h>
int main(void)
{
int counter = 100;
while (counter >= 0)
{
printf("%i\n", counter);
counter -= 1;
}
}
10
31 Programming Fundamental Problems – C Language
Problem 8
#include <cs50.h>
#include <stdio.h>
int main(void)
{
// Prompt user for x
int x = get_int("x: ");
// Prompt user for y
int y = get_int("y: ");
// Compare x and y
if (x == y)
{
printf("YES\n");
}
else
{
printf("NO\n");
}
}
11
31 Programming Fundamental Problems – C Language
Problem 9
#include <stdio.h>
void say_hello(void);
int main(void)
{
say_hello();
}
void say_hello()
{
printf("hello\n");
}
Problem 10
#include <stdio.h>
void say_hello(int x);
int main(void)
{
say_hello(4);
}
12
31 Programming Fundamental Problems – C Language
void say_hello(int x)
{
for (int i = 0; i < x; i++)
{
printf("Hello\n");
}
}
Problem 11
#include <stdio.h>
int double_num(int x);
int main(void)
{
int result = double_num(4);
printf("%i\n", result);
printf("%i\n", double_num(5));
printf("%i\n", double_num(6));
printf("%i\n", double_num(7));
}
int double_num(int x)
{
return 2*x;
}
13
31 Programming Fundamental Problems – C Language
Problem 12
#include <stdio.h>
void cough(int x);
int main(void)
{
printf("Cough\n");
printf("Cough\n");
printf("Cough\n");
for (int i = 0; i < 3; i ++)
{
printf("Cough\n");
}
cough(3);
}
void cough(int x)
{
for (int i = 0; i < 3; i ++)
{
printf("Cough\n");
}
}
14
31 Programming Fundamental Problems – C Language
Problem 13
#include <cs50.h>
#include <stdio.h>
int test(int x, int y);
int main(void)
{
int a = get_int("What is the first number?\n");
int b = get_int("What is the second number?\n");
int result = test(a, b);
printf("The result is %d\n", result);
}
int test(int x, int y)
{
if (x == y)
{
return 3*(x+y);
}
else
{
return x + y;
}
}
15
31 Programming Fundamental Problems – C Language
Problem 14
#include <cs50.h>
#include <stdio.h>
int test(int x, int y);
int main(void){
int a = get_int("What is the first number?\n");
int b = get_int("What is the second number?\n");
int result = test(a, b);
printf("The result is %d\n", result);
}
int test(int x, int y)
{
return x == 30 || y == 30 || (x + y == 30);
}
Problem 15
#include <stdio.h>
int main(void){
int sum = 0;
for (int j = 1; j <= 10; j++)
{
sum = sum + j;
}
printf("\nThe Sum is : %d\n", sum);
}
16
31 Programming Fundamental Problems – C Language
Problem 16
#include <stdio.h>
int test(int x, int y);
int main(void)
{
printf("%d\n",test(100, 199));
printf("%d\n",test(250, 300));
printf("%d\n",test(105, 190));
}
int test(int x, int y)
{
return (x >= 100 && x <= 200) || (y >= 100 && y <= 200);
}
Problem 17
#include <cs50.h>
#include <stdio.h>
int main(void)
{
// Prompt user for integer
int n = get_int("n: ");
17
31 Programming Fundamental Problems – C Language
// Check parity of integer
if (n % 2 == 0)
{
printf("even\n");
}
else
{
printf("odd\n");
}
}
Problem 18
#include <cs50.h>
#include <stdio.h>
int main(void)
{
int x = get_int("What's your change?\n");
int count_of_quarters = 0;
while (x >= 25)
{
x -= 25;
count_of_quarters += 1;
}
printf("%d\n", count_of_quarters);
}
18
31 Programming Fundamental Problems – C Language
Problem 19
#include <cs50.h>
#include <stdio.h>
int get_positive_int(void);
int main(void)
{
int i = get_positive_int();
printf("%i\n", i);
}
// Prompt user for positive integer
int get_positive_int(void)
{
int n;
do
{
n = get_int("Positive Integer: ");
}
while (n);
return n;
}
19
31 Programming Fundamental Problems – C Language
Problem 20
#include <stdlib.h>
#include <stdio.h>
int test(int x, int y);
int main(void)
{
printf("%d\n",test(78, 95));
printf("%d\n",test(95, 95));
printf("%d\n",test(99, 70));
}
int test(int x, int y)
{
int val = abs(x - 100);
int val2 = abs(y - 100);
if (val == val2)
{
return 0;
}
else
{
if (val < val2)
{
return x;
}
20
31 Programming Fundamental Problems – C Language
else
{
return y;
}
}
}
Problem 21
#include <stdlib.h>
#include <stdio.h>
int test(int x, int y);
int main(void)
{
printf("%d\n",test(123, 456));
printf("%d\n",test(12, 512));
printf("%d\n",test(7, 87));
printf("%d\n",test(12, 45));
}
int test(int x, int y)
{
return abs(x % 10) == abs(y % 10);
}
21
31 Programming Fundamental Problems – C Language
Problem 22
#include <stdlib.h>
#include <stdio.h>
int test(int x, int y);
int main(void)
{
printf("%d\n",test(123, 456));
printf("%d\n",test(12, 512));
printf("%d\n",test(7, 87));
printf("%d\n",test(12, 45));
}
int test(int x, int y)
{
if (a + b >= 10 && a + b <= 20)
{
return 30;
}
else
{
return a + b;
}
}
22
31 Programming Fundamental Problems – C Language
Problem 23
#include <stdlib.h>
#include <stdio.h>
int test(int x, int y);
int main(void)
{
printf("%d\n",test(5, 4));
printf("%d\n",test(4, 3));
printf("%d\n",test(1, 4));
}
int test(int x, int y)
{
return x == 5 || y == 5 || x + y == 5 || abs(x - y) == 5;
}
Problem 24
#include <stdio.h>
int main(void){
for (int i = 0; i <= 50; i++)
{
if (i % 3 == 0 && i % 5 == 0)
23
31 Programming Fundamental Problems – C Language
{
printf("Fizzbuzz\n");
}
else if (i % 3 == 0)
{
printf("Fizz\n");
}
else if (i % 5 == 0)
{
printf("Buzz\n");
}
else
{
printf("%d\n", i);
}
}
}
Problem 25
#include <cs50.h>
#include <stdio.h>
int main(void)
{
int rows = get_int("Input no. of rows:\n");
for(int i=1;i<=rows;i++)
{
24
31 Programming Fundamental Problems – C Language
for(int j=1;j<=i;j++)
{
printf("*\n");
}
}
}
Problem 26
#include <cs50.h>
#include <stdio.h>
int main(void)
{
int rows = get_int("Input number of rows : ");
for(int i = 1;i <= rows; i++)
{
for(int j = 1;j <= i;j++)
{
printf("%d",i);
}
printf("\n");
}
}
25
31 Programming Fundamental Problems – C Language
Problem 27
#include <cs50.h>
#include <stdio.h>
int main(void)
{
int k=1;
rows = get_int("Input number of rows :\n ");
for(int i=1;i<=rows;i++)
{
for(int j=1;j<=i;j++)
{
printf("%d ",k);
k++;
}
printf("\n");
}
}
Problem 28
#include <cs50.h>
#include <stdio.h>
int get_num_digits(long card_num);
26
31 Programming Fundamental Problems – C Language
int main(void)
{
int num = get_int("What's your number? \n");
int num_digits = get_num_digits(num);
printf("Your number has %d digits\n", num_digits);
}
int get_num_digits(long card_num)
{
int count = 0;
while (card_num != 0)
{
card_num /= 10;
count += 1;
}
return count;
}
Problem 29
#include <cs50.h>
#include <stdio.h>
int sum_digits(long card_num);
27
31 Programming Fundamental Problems – C Language
int main(void)
{
int num = get_int("What's your number? \n");
int num_digits = sum_digits(num);
printf("Your number sum of digits is %d\n", num_digits);
}
int sum_digits(long card_num)
{
int sum = 0;
while (card_num > 0)
{
sum += (card_num % 10)
card_num /= 10;
}
return sum;
}
Problem 30
#include <cs50.h>
#include <stdio.h>
int sum_every_other_digit(long card_num);
28
31 Programming Fundamental Problems – C Language
int main(void)
{
int num = get_int("What's your number? \n");
int num_digits = sum_every_other_digit(num);
printf("Sum of every other digit is %d\n", num_digits);
}
int sum_every_other_digit(long card_num)
{
int isAlternateDigit = false;
int sum = 0;
while (card_num > 0)
{
if (isAlternateDigit)
{
sum += (card_num % 10)
}
isAlternateDigit = !isAlternateDigit;
card_num /= 10;
}
return sum;
}
Problem 31
#include <math.h>
#include <stdio.h>
29
31 Programming Fundamental Problems – C Language
int main(void)
{
int num = 23032234;
int first_two_digits1 = 23032234 / 1000000;
int first_two_digits2 = 23032234 / pow(10, 6);
}
30
12 Arrays Problems – C Language
Questions
Problem 1
Create an array with 10 elements. Print the elements of the array
Problem 2
Create an array with 10 elements. Sum the value of all elements. Print the
result.
Problem 3
Create an array with 10 elements. Calculate the average of them. Print the
result.
Problem 4
Create a character variable. Print its ASCII value.
Problem 5
Ask user for their name. Print every single character of their name.
Problem 6
Ask user for their name. Print every single ASCII number of letters in their
name.
Problem 7
Ask user for their name with all letters in lowercase. Print how far each letter
is from 'a' in ASCII table.
2
12 Arrays Problems – C Language
Problem 8
Ask user for an string input. Capitalize all letter without using isLower() or
toUpper().
Problem 9
Ask user for an string input. Capitalize all letter using isLower() or toUpper().
Problem 10
Cryptography is the art of scrambling, or hiding information. One way of doing
that is to add a number to the ASCII value to letters of a string.
Example:
ORIGINAL
String: I L O V E Y O U
ASCII: 73 76 79 86 69 89 79 85
Adding +1
AFTER CRYPTOGRAPHY
ASCII
74 77 80 87 70 90 80 86
STRING J M P W F Z P V
Store the variable ILOVEYOU in a string. Add 1 to each letter. Print the
encrypted message (JMPWFZPV).
3
12 Arrays Problems – C Language
Problem 11
Create a program that prints the second argument if the command line if
number of arguments is 2. Print hello world otherwise.
Problem 12
Print all letters of the second argument from the command line if the number
of arguments equals 2.
Solutions
4
12 Arrays Problems – C Language
Problem 1
#include <stdio.h>
int main(void)
{
int a[10] = {8, 4, 2, 1, 4, 9, 6, 7, 8, 9};
for (int i = 0; i < 10; i++)
{
printf("%d\n", a[i]);
}
}
Problem 2
#include <stdio.h>
int main(void)
{
int a[10] = {8, 4, 2, 1, 4, 9, 6, 7, 8, 9};
int sum = 0;
for (int i = 0; i < 10; i++)
{
sum += a[i];
}
printf("%d\n", sum);
}
5
12 Arrays Problems – C Language
Problem 3
#include <stdio.h>
int main(void)
{
int a[10] = {8, 4, 2, 1, 4, 9, 6, 7, 8, 9};
int sum = 0;
for (int i = 0; i < 10; i++)
{
sum += a[i];
}
float average = (float) sum / 10;
printf("%0.2f\n", average);
}
Problem 4
#include <stdio.h>
int main(void)
{
char c = 'a';
printf("%i\n", c);
}
Problem 5
6
12 Arrays Problems – C Language
#include <stdio.h>
#include <cs50.h>
#include <string.h>
int main(void)
{
string s = get_string("Input: \n");
for (int i = 0; i < strlen(s); i++)
{
printf("%c", s[i]);
}
printf("\n");
}
Problem 6
#include <stdio.h>
#include <cs50.h>
#include <string.h>
int main(void)
{
string s = get_string("Input: \n");
for (int i = 0; i < strlen(s); i++)
{
printf("%i", s[i]);
}
printf("\n");
}
Problem 7
7
12 Arrays Problems – C Language
#include <stdio.h>
#include <cs50.h>
#include <string.h>
int main(void)
{
string s = get_string("Input: \n");
for (int i = 0; i < strlen(s); i++)
{
printf("%i", s[i] - 'a');
}
printf("\n");
}
Problem 8
#include <stdio.h>
#include <cs50.h>
#include <string.h>
int main(void)
{
string s = get_string("Before: ");
printf("After: ");
for (int i = 0, n = strlen(s); i < n; i++)
{
if (s[i] >= 'a' && s[i] <= 'z')
{
8
12 Arrays Problems – C Language
printf("%c", s[i] - 32);
}
else
{
printf("%c", s[i]);
}
}
printf("\n");
}
Problem 9
#include <stdio.h>
#include <cs50.h>
#include <string.h>
#include <ctype.h>
int main(void)
{
string s = get_string("Before: ");
printf("After: ");
for (int i = 0, n = strlen(s); i < n; i++)
{
if (islower(s[i]))
{
printf("%c", toupper(s[i]));
}
else
9
12 Arrays Problems – C Language
{
printf("%c", s[i]);
}
}
printf("\n");
}
Problem 10
#include <stdio.h>
#include <cs50.h>
#include <ctype.h>
int main(void)
{
string s = "ILOVEYOU";
printf("After: ");
for (int i = 0, n = strlen(s); i < n; i++)
{
printf("%c", s[i] + 1);
}
}
Problem 11
#include <stdio.h>
#include <cs50.h>
int main(int argc, string argv[])
10
12 Arrays Problems – C Language
{
if (argc == 2)
{
printf("hello, %s\n", argv[1]);
}
else
{
printf("hello, world\n");
}
}
Problem 12
#include <stdio.h>
#include <cs50.h>
#include <string.h>
int main(int argc, string argv[])
{
if (argc == 2)
{
for (int i = 0, n = strlen(argv[1]); i < n; i++)
{
printf("%c\n", argv[1][i]);
}
}
}
11
3 Problems of Structs – C Language
Questions
Problem 1
Create a struct called student with two properties: name and student_id.
Initialize those properties. Print them.
Problem 2
Create an array of student structs (same from problem1). Initialize each one
of them. Print the name and student_id of one of them.
Problem 3
Implement Bubble Sort with an array of 6 elements.
2
3 Problems of Structs – C Language
Solutions
Problem 1
#include <cs50.h>
#include <stdio.h>
#include <string.h>
typedef struct
{
string name;
int student_id;
}
student;
int main(void)
{
student p1;
p1.name = "RODRIGO";
p1.student_id = 4;
printf("%d\n", p1.student_id);
printf("%s\n", p1.name);
}
3
3 Problems of Structs – C Language
Problem 2
#include <cs50.h>
#include <stdio.h>
#include <string.h>
typedef struct
{
string name;
int student_id;
}
student;
int main(void)
{
student students[3];
students[0].name = "RODRIGO";
students[0].student_id = 4;
students[1].name = "ELLA";
students[1].student_id = 5;
students[2].name = "MARLENE";
students[2].student_id = 6;
printf("%d\n", students[0].student_id);
printf("%s\n", students[2].name);
}
4
3 Problems of Structs – C Language
Problem 3
#include <stdio.h>
#include <cs50.h>
int main()
{
int array[6] = {5, 4, 2, 1, 10, 3};
for (int i = 0 ; i < 5; i++)
{
for (int j = 0 ; j < 6 - i - 1; j++)
{
if (array[j] > array[j+1]) /* For decreasing order use '<' instead of '>' */
{
int swap = array[j];
array[j] = array[j+1];
array[j+1] = swap;
}
}
}
printf("Sorted list in ascending order:\n");
for (int i = 0; i < 6; i++)
printf("%d\n", array[i]);
return 0;
}
5
10 Problems of Data Structures – C Language
Questions
Problem 1
Create a struct with int properties of a car. Put struct in a variable called audi.
Create a pointer called ptr that points to this struct. Print the same property using:
a) (*ptr).propertyName
b) ptr->propertyName
c) audi.propertyName
Problem 2
Create a linked list with 3 nodes.
Problem 3
Using the linked list from last problem, print the values of the nodes in a linked
list.
Problem 4
Using linked list from last problem, insert node at the front of a linked list.
Problem 5
Using linked list from last problem, delete node from the front of a linked list.
Problem 6
Using linked list from previous problem, free them from memory.
Problem 7
Create a person struct that has as properties:
a) Two pointers to two other "person" structs
2
10 Problems of Data Structures – C Language
b) A char array with two elements called alleles
Then create a person with two parents (which are also person structs). Print
one of the parent’s alleles.
Problem 8
Using the struct from last problem. Free them from memory.
Problem 9
Create an array of 5 pointers. The pointers point to a LinkedList Node. Create
a new node. Make the pointer at index 0 point to the new node.
Problem 10
Create an array of 5 pointers. The pointers point to a LinkedList Node. Create
a new node. Make the pointer at index 0 point to this new node. Create a second new
node. Add this second node at index 0 as well (before node you created previously).
3
10 Problems of Data Structures – C Language
Solutions
Problem 1
#include <stdio.h>
typedef struct{
int km;
int kph;
int kg;
} car;
int main(void){
car audi = {12000, 230, 760};
car *ptr = &audi;
printf("%d\n", (*ptr).km);
printf("%d\n", ptr->km);
printf("%d\n", audi.km);
}
4
10 Problems of Data Structures – C Language
Problem 2
#include <stdio.h>
#include <stdlib.h>
// Represents a node
typedef struct node
{
int number;
struct node *next;
}
node;
int main(void)
{
// List of size 0, initially not pointing to anything
node *list = NULL;
// Add number to list
node *n = malloc(sizeof(node));
if (n == NULL)
{
return 1;
}
n->number = 1;
n->next = NULL;
// We create our first node, store the value 1 in it, and leave the next
// pointer to point to nothing. Then, our list variable can point to it.
5
10 Problems of Data Structures – C Language
list = n;
// Add number to list
n = malloc(sizeof(node));
if (n == NULL)
{
return 1;
}
n->number = 2;
n->next = NULL;
// Now, we go our first node that list points to, and sets the next pointer
// on it to point to our new node, adding it to the end of the list:
list->next = n;
// Add number to list
n = malloc(sizeof(node));
if (n == NULL)
{
return 1;
}
n->number = 3;
n->next = NULL;
// We can follow multiple nodes with this syntax, using the next pointer
// over and over, to add our third new node to the end of the list:
list->next->next = n;
}
6
10 Problems of Data Structures – C Language
Problem 3
#include <stdio.h>
#include <stdlib.h>
// Represents a node
typedef struct node
{
int number;
struct node *next;
}
node;
int main(void)
{
// List of size 0, initially not pointing to anything
node *list = NULL;
// Add number to list
node *n = malloc(sizeof(node));
n->number = 1;
n->next = NULL;
// We create our first node, store the value 1 in it, and leave the next
// pointer to point to nothing. Then, our list variable can point to it.
list = n;
// Add number to list
n = malloc(sizeof(node));
7
10 Problems of Data Structures – C Language
n->number = 2;
n->next = NULL;
// Now, we go our first node that list points to, and sets the next pointer
// on it to point to our new node, adding it to the end of the list:
list->next = n;
// Add number to list
n = malloc(sizeof(node));
n->number = 3;
n->next = NULL;
// We can follow multiple nodes with this syntax, using the next pointer
// over and over, to add our third new node to the end of the list:
list->next->next = n;
node * temp = list;
while (temp != NULL)
{
printf("%d\n", temp->number);
temp = temp->next;
}
}
8
10 Problems of Data Structures – C Language
Problem 4
#include <stdio.h>
#include <stdlib.h>
// Represents a node
typedef struct node
{
int number;
struct node *next;
}
node;
int main(void)
{
// List of size 0, initially not pointing to anything
node *list = NULL;
// Add number to list
node *n = malloc(sizeof(node));
n->number = 1;
n->next = NULL;
// We create our first node, store the value 1 in it, and leave the next
// pointer to point to nothing. Then, our list variable can point to it.
list = n;
// Add number to list
n = malloc(sizeof(node));
9
10 Problems of Data Structures – C Language
n->number = 2;
n->next = NULL;
// Now, we go our first node that list points to, and sets the next pointer
// on it to point to our new node, adding it to the end of the list:
list->next = n;
// Add number to list
n = malloc(sizeof(node));
n->number = 3;
n->next = list;
// We can follow multiple nodes with this syntax, using the next pointer
// over and over, to add our third new node to the end of the list:
list = n;
}
Problem 5
#include <stdio.h>
#include <stdlib.h>
// Represents a node
typedef struct node
{
int number;
struct node *next;
}
node;
10
10 Problems of Data Structures – C Language
void printLL(node * temp);
int main(void)
{
// List of size 0, initially not pointing to anything
node *list = NULL;
// Add number to list
node *n = malloc(sizeof(node));
n->number = 1;
n->next = NULL;
// We create our first node, store the value 1 in it, and leave the next
// pointer to point to nothing. Then, our list variable can point to it.
list = n;
// Add number to list
n = malloc(sizeof(node));
n->number = 2;
n->next = NULL;
// Now, we go our first node that list points to, and sets the next pointer
// on it to point to our new node, adding it to the end of the list:
list->next = n;
// Add number to list
n = malloc(sizeof(node));
11
10 Problems of Data Structures – C Language
n->number = 3;
n->next = NULL;
// We can follow multiple nodes with this syntax, using the next pointer
// over and over, to add our third new node to the end of the list:
list->next->next = n;
node *toDelete = list;
list = list->next;
free(toDelete);
node * temp = list;
while (temp != NULL)
{
printf("%d\n", temp->number);
temp = temp->next;
}
}
Problem 6
#include <stdio.h>
#include <stdlib.h>
// Represents a node
typedef struct node
{
int number;
struct node *next;
12
10 Problems of Data Structures – C Language
}
node;
void freelist(node *temp);
int main(void)
{
// List of size 0, initially not pointing to anything
node *list = NULL;
// Add number to list
node *n = malloc(sizeof(node));
n->number = 1;
n->next = NULL;
// We create our first node, store the value 1 in it, and leave the next
// pointer to point to nothing. Then, our list variable can point to it.
list = n;
// Add number to list
n = malloc(sizeof(node));
n->number = 2;
n->next = NULL;
// Now, we go our first node that list points to, and sets the next pointer
// on it to point to our new node, adding it to the end of the list:
list->next = n;
// Add number to list
13
10 Problems of Data Structures – C Language
n = malloc(sizeof(node));
n->number = 3;
n->next = NULL;
// We can follow multiple nodes with this syntax, using the next pointer
// over and over, to add our third new node to the end of the list:
list->next->next = n;
freelist(list);
}
void freelist(node *temp)
{
if (temp == NULL)
{
return;
}
freelist(temp->next);
free(temp);
}
Problem 7
#include <stdio.h>
#include <stdlib.h>
typedef struct person
14
10 Problems of Data Structures – C Language
{
struct person *parents[2];
char alleles[2];
}
person;
int main(void){
person *p1 = malloc(sizeof(person));
p1->alleles[0] = 'A';
p1->alleles[1] = 'O';
p1->parents[0] = NULL;
p1->parents[1] = NULL;
person *p2 = malloc(sizeof(person));
p2->alleles[0] = 'A';
p2->alleles[1] = 'B';
p2->parents[0] = NULL;
p2->parents[1] = NULL;
person *child = malloc(sizeof(person));
child->alleles[0] = 'A';
child->alleles[1] = 'A';
child->parents[0] = p1;
child->parents[1] = p2;
printf("%c\n", child->parents[1]->alleles[1]);
15
10 Problems of Data Structures – C Language
}
Problem 8
#include <stdio.h>
#include <stdlib.h>
typedef struct person
{
struct person *parents[2];
char alleles[2];
}
person;
void free_family(person *p);
int main(void){
person *p1 = malloc(sizeof(person));
p1->alleles[0] = 'A';
p1->alleles[1] = 'O';
p1->parents[0] = NULL;
p1->parents[1] = NULL;
person *p2 = malloc(sizeof(person));
p2->alleles[0] = 'A';
p2->alleles[1] = 'B';
16
10 Problems of Data Structures – C Language
p2->parents[0] = NULL;
p2->parents[1] = NULL;
person *child = malloc(sizeof(person));
child->alleles[0] = 'A';
child->alleles[1] = 'A';
child->parents[0] = p1;
child->parents[1] = p2;
free_family(child);
}
// Free `p` and all ancestors of `p`.
void free_family(person *p)
{
// TODO: Handle base case
if (p == NULL)
{
return;
}
// TODO: Free parents
free_family(p->parents[0]);
free_family(p->parents[1]);
// TODO: Free child
free(p);
}
17
10 Problems of Data Structures – C Language
Problem 9
#include <stdlib.h>
#include <stdio.h>
// Represents a node in a hash table
typedef struct node
{
int x;
struct node *next;
}
node;
int main(void)
{
// Hash table
node *table[5];
//Create space for a node
node *temp = malloc(sizeof(node));
//Set next field of temp to NULL
temp->next = NULL;
//Set pointer at 0 to node
table[0] = temp;
}
18
10 Problems of Data Structures – C Language
Problem 10
#include <stdlib.h>
#include <stdio.h>
// Represents a node in a hash table
typedef struct node
{
int x;
struct node *next;
}
node;
int main(void)
{
// Hash table
node *table[5];
//Create space for a node
node *temp1 = malloc(sizeof(node));
//Set next field of temp to NULL
temp1->next = NULL;
//Set pointer at 0 to node
table[0] = temp1;
node *temp2 = malloc(sizeof(node));
temp2->next = temp1;
table[0] = temp2;
}
19
6 Problems of C Pointers – C Language
Questions
Problem 1
Create an integer. Print the address of an integer.
Problem 2
Create an integer. Grab the address of the integer and dereference it (you
should see an integer).
Problem 3
Create an integer. Create a pointer to the integer. Print the address of the
pointer. Print the address of the integer (using the pointer). Print the value of the
integer (using the pointer).
Problem 4
Create a function that swaps two integers. Swap by first passes the addresses
of the integers. Then swap them pack by passing as arguments pointers to the
integers.
Problem 5
Crete an integer. Create a pointer to that integer. Create a function that takes
the pointer as input and adds one to the integer.
Problem 6
Create a char pointer to a string with three characters. Print each character
using pointer arithmetic.
Problem 7
Ask user for input. Copy the string.
2
6 Problems of C Pointers – C Language
Solutions
Problem 1
#include <stdio.h>
int main()
{
int num = 5;
printf("%p\n", &num);
}
Problem 2
#include <stdio.h>
int main()
{
int num = 5;
printf("%d\n", *&num);
}
Problem 3
#include <stdio.h>
int main() {
int num = 5;
int *ptr = &num;
printf("%p\n", &ptr);
printf("%p\n", ptr);
printf("%d\n", *ptr);
}
3
6 Problems of C Pointers – C Language
Problem 4
#include <stdio.h>
void swap(int *x, int *y);
int main() {
int a = 3;
int b = 4;
swap(&a, &b);
printf("First swap");
printf("%d\n", a);
printf("%d\n", b);
int *r = &a;
int *s = &b;
swap(r, s);
printf("Swap back");
printf("%d\n", a);
printf("%d\n", b);
}
void swap(int *x, int *y)
{
int temp = *x;
*x = *y;
*y = temp;
}
4
6 Problems of C Pointers – C Language
Problem 5
#include <stdio.h>
void addOne(int* ptr) {
*ptr = *ptr + 1 // adding 1 to *ptr
}
int main()
{
int i = 10;
int *p = &i;
addOne(p);
printf("%d", *p); // 11
return 0;
}
Problem 6
#include <stdio.h>
int main(void)
{
char *s = "HI!";
printf("%c\n", *s);
printf("%c\n", *(s+1));
printf("%c\n", *(s+2));
}
5
6 Problems of C Pointers – C Language
Problem 7
#include <cs50.h>
#include <ctype.h>
#include <stdio.h>
#include <string.h>
int main(void)
{
char *s = get_string("s: ");
char *t = malloc(strlen(s) + 1);
for (int i = 0, n = strlen(s); i < n + 1; i++)
{
t[i] = s[i];
}
t[0] = toupper(t[0]);
printf("s: %s\n", s);
printf("t: %s\n", t);
}
6
Python and Scratch
Correlating Scratch with Python
Introduction
Operators
2
Python and Scratch
3
Python and Scratch
Loops
4
Python and Scratch
Conditionals
5
Python and Scratch
Lists
6
Python and Scratch
Functions
7
Python and Scratch
8
30 Programming Fundamental Problems – Python
Questions
Problem 1
Create a list. Loop through the list using:
1. For each
2. For index
3. For loop value with index
Problem 2
Print the values from 1 to 100.
Problem 3
Print from 0 to 100, only the even numbers. Use for loops.
Problem 4
Sum numbers from 1 to 100.
Problem 5
Add 1 + 3 + 5 + … + 99
Problem 6
Loop from 100 to 1. Print the values.
Problem 7
Add all the numbers from 99 + 97 + 95 + … + 1
Problem 8
Create an integer. Print if the integer is even or odd.
2
30 Programming Fundamental Problems – Python
Problem 9
Create two integers. Check if they have the same last digit. Print YES if they
are the same. Print NO if they are not the same.
Problem 10
Loop through values from 1 to 100 inclusive. Check the conditions:
▪
▪
▪
▪
If the current number is divisible by 3, print Fizz.
If the current number is divisible by 5, print Buzz.
If the current number is divisible by both 3 and 5, print FizzBuzz.
Else, print the number.
Problem 11
Repeat problem 1, but with a string.
Problem 12
Create a string. Print the first letter.
Problem 13
Create a string. Print the last letter.
Problem 14
Create a string. Print the string without the first letter.
Problem 15
Create a string. Print the string without the last letter.
Problem 16
Create a string with value apple. Print ppl.
3
30 Programming Fundamental Problems – Python
Problem 17
Create a long string. Print two letters at a time.
Problem 18
Create a long string. Print two letters at a time, without overlapping letters.
Problem 19
Create a string. Print three letters at a time.
Problem 20
Create two strings. Concatenate the second with the first.
Problem 21
Create an empty list. Append a number to this list.
Problem 22
Create a list. Add values 1 to 100.
Problem 23
Create a list. Add values 1 + 3 + 5 + … + 99 to list. Loop through the list and add
all numbers inside of it.
Problem 24
Add numbers from 1 to 100 using a while loop.
Problem 25
Create an integer. Count the number of digits.
4
30 Programming Fundamental Problems – Python
Problem 26
Create a long number. Grab the first two digits.
Problem 27
Create the following pattern:
*
**
***
****
Problem 28
Create a list of strings (with more than 4 letters). Print the 3rd letter of the 2nd
string.
Problem 29
Create a list with multiple numbers. Print the number in reverse order using
a loop.
Problem 30
Create a list called even. Create another list called odd. Loop through the
values from 1 to 100. If number is even, add it to even list. If number is odd, add it to
odd list.
5
30 Programming Fundamental Problems – Python
Solutions
Problem 1
x = [10, 9, 5, 3, 2]
#for each loop
for val in x:
print(val)
#loop through the list index
for i in range(len(x)):
print(i)
#loop through the values of the list
#using the index
for i in range(len(x)):
print(x[i])
Problem 2
for i in range(1, 101):
print(i)
Problem 3
for i in range(0, 101, 2):
print(i)
6
30 Programming Fundamental Problems – Python
Problem 4
sum = 0
for i in range(1, 11):
sum = sum + i
print(sum)
Problem 5
sum = 0
for i in range(1, 100, 2):
sum += i
print(sum)
Problem 6
for i in range(100, 0, -1):
print(i)
Problem 7
sum = 0
for i in range(99, 0, -2):
sum += i
print(sum)
7
30 Programming Fundamental Problems – Python
Problem 8
num = 21
if num % 2 == 0:
print("even")
else:
print("odd")
Problem 9
num1 = 13
num2 = 13
if (num1 % 10) == (num2 % 10):
print("YES")
else:
print("NO")
Problem 10
for i in range(1, 101):
if (i % 3 == 0 and i % 5 == 0):
print("FIZZBUZZ")
elif (i % 3 == 0):
print("FIZZ")
elif (i % 5 == 0):
print("BUZZ")
else:
print(i)
8
30 Programming Fundamental Problems – Python
Problem 11
text = "coding"
#for each loop
for char in text:
print(char)
#printing index
for index in range(len(text)):
print(index)
#print the letters using the index with for loop
for i in range(len(text)):
print(text[i])
Problem 12
text = "coding"
print(text[0])
Problem 13
text = "codingasdasdasdasda"
print(text[len(text)-1])
Problem 14
text = "coding"
print(text[1:])
9
30 Programming Fundamental Problems – Python
Problem 15
text = "coding"
print(text[0:len(text)-1])
Problem 16
text = "apple"
print(text[1:4])
Problem 17
text = "applebanana"
for i in range(0, len(text)-1):
print(text[i:i+2])
Problem 18
text = "applefab"
for i in range(0, len(text)-1, 2):
print(text[i:i+2])
Problem 19
text = "applebananas"
for i in range(0, len(text)-1, 3):
print(text[i:i+3])
10
30 Programming Fundamental Problems – Python
Problem 20
text1 = "banana"
text2 = "apple"
#text1 = text1 + text2
text1 += text2
print(text1)
Problem 21
x = []
x.append(10)
print(x)
Problem 22
x = []
for i in range(1, 101):
x.append(i)
print(x)
Problem 23
x = []
for i in range(1, 100, 2):
x.append(i)
sum = 0
for val in x:
sum += val
print(sum)
11
30 Programming Fundamental Problems – Python
Problem 24
counter = 0
sum = 0
while (counter <= 100):
sum+= counter
counter += 1
print(sum)
Problem 25
num = 231231231
counter = 0
while num > 0:
num = num // 10
counter += 1
print(counter)
Problem 26
num = 23423323
print(num // pow(10, 6))
Problem 27
for row in range(1, 5):
for col in range(1, row+1):
print("*", end="")
print()
12
30 Programming Fundamental Problems – Python
Problem 28
x = ["apple", "banana", "watermellon", "lemon"]
print(x[1][2])
Problem 29
x = [9, 3, 5, 3, 2, 1, 0]
for i in range(len(x)-1, -1, -1):
print(x[i])
Problem 30
even = []
odd = []
for i in range(1, 10):
if i % 2 == 0:
even.append(i)
else:
odd.append(i)
print(even)
print(odd)
13
CodingBat Warmup 1 - Python
Questions
sleep_in
The parameter weekday is True if it is a weekday, and the parameter vacation
is True if we are on vacation. We sleep in if it is not a weekday or we're on vacation.
Return True if we sleep in.
sleep_in(False, False) → True
sleep_in(True, False) → False
sleep_in(False, True) → True
monkey_trouble
We have two monkeys, a and b, and the parameters a_smile and b_smile
indicate if each is smiling. We are in trouble if they are both smiling or if neither of
them is smiling. Return True if we are in trouble.
monkey_trouble(True, True) → True
monkey_trouble(False, False) → True
monkey_trouble(True, False) → False
sum_double
Given two int values, return their sum. Unless the two values are the same,
then return double their sum.
sum_double(1, 2) → 3
sum_double(3, 2) → 5
sum_double(2, 2) → 8
2
CodingBat Warmup 1 - Python
diff21
Given an int n, return the absolute difference between n and 21, except return
double the absolute difference if n is over 21.
diff21(19) → 2
diff21(10) → 11
diff21(21) → 0
parrot_trouble
We have a loud talking parrot. The "hour" parameter is the current hour time
in the range 0..23. We are in trouble if the parrot is talking and the hour is before 7
or after 20. Return True if we are in trouble.
parrot_trouble(True, 6) → True
parrot_trouble(True, 7) → False
parrot_trouble(False, 6) → False
makes10
Given 2 ints, a and b, return True if one if them is 10 or if their sum is 10.
makes10(9, 10) → True
makes10(9, 9) → False
makes10(1, 9) → True
near_hundred
Given an int n, return True if it is within 10 of 100 or 200. Note: abs(num)
computes the absolute value of a number.
3
CodingBat Warmup 1 - Python
near_hundred(93) → True
near_hundred(90) → True
near_hundred(89) → False
pos_neg
Given 2 int values, return True if one is negative and one is positive. Except if
the parameter "negative" is True, then return True only if both are negative.
pos_neg(1, -1, False) → True
pos_neg(-1, 1, False) → True
pos_neg(-4, -5, True) → True
not_string
Given a string, return a new string where "not " has been added to the front.
However, if the string already begins with "not", return the string unchanged.
not_string('candy') → 'not candy'
not_string('x') → 'not x'
not_string('not bad') → 'not bad'
missing_char
Given a non-empty string and an int n, return a new string where the char at
index n has been removed. The value of n will be a valid index of a char in the original
string (i.e. n will be in the range 0..len(str)-1 inclusive).
missing_char('kitten', 1) → 'ktten'
missing_char('kitten', 0) → 'itten'
missing_char('kitten', 4) → 'kittn'
4
CodingBat Warmup 1 - Python
front_back
Given a string, return a new string where the first and last chars have been
exchanged.
front_back('code') → 'eodc'
front_back('a') → 'a'
front_back('ab') → 'ba'
front3
Given a string, we'll say that the front is the first 3 chars of the string. If the
string length is less than 3, the front is whatever is there. Return a new string which
is 3 copies of the front.
front3('Java') → 'JavJavJav'
front3('Chocolate') → 'ChoChoCho'
front3('abc') → 'abcabcabc'
5
CodingBat Warmup 1 - Python
Solutions
sleep_in
def sleep_in(weekday,vacation):
if not weekday or vacation:
return True
else:
return False
monkey_trouble
def monkey_trouble(a_smile,b_smile):
if a_smile and b_smile:
return True
if not a_smile and not b_smile:
return False
sum_double
def sum_double(a,b):
if a == b:
return 2 * (a + b)
else:
return a + b
diff21
def diff21(n):
6
CodingBat Warmup 1 - Python
if n > 21:
return 2 * abs(n - 21)
else:
return abs(n - 21)
parrot_trouble
def parrot_trouble(talking,hour):
if talking and (hour < 7 or hour > 20):
return True
else:
return False
makes10
def makes10(a,b):
if (a + b == 10) or a == 10 or b == 10:
return True
else:
return False
near_hundred
def near_hundred(n):
if abs(n - 100) <= 10 or abs(n - 200) <= 10:
return True
else:
return False
7
CodingBat Warmup 1 - Python
pos_neg
def pos_neg(a,b,negative):
if (a < 0 and b < 0) and negative is True:
return True
elif negative is True:
return False
elif (a > 0 and b < 0) or (a < 0 and b > 0):
return True
else:
return False
not_string
def not_string(str):
if len(str) >= 3 and str[:3] == “not”:
return str
return “not” + str
missing_char
def missing_char(str,n):
front = str[:n]
back = str[n+1:]
return front + back
8
CodingBat Warmup 1 - Python
front_back
def front_back(str):
if len(str) <= 1:
return str
mid = str[1: len(str)-1]
return str[len(str)-1] + mid + str[0]
front3
def front3(str):
front_end = 3
if len(str) < front_end:
front_end = len(str)
front = str[:front_end]
return front + front + front
9
CodingBat String 1 - Python
Questions
hello_name
Given a string name, e.g. "Bob", return a greeting of the form "Hello Bob!".
hello_name('Bob') → 'Hello Bob!'
hello_name('Alice') → 'Hello Alice!'
hello_name('X') → 'Hello X!'
make_abba
Given two strings, a and b, return the result of putting them together in the
order abba, e.g. "Hi" and "Bye" returns "HiByeByeHi".
make_abba('Hi', 'Bye') → 'HiByeByeHi'
make_abba('Yo', 'Alice') → 'YoAliceAliceYo'
make_abba('What', 'Up') → 'WhatUpUpWhat'
make_tags
The web is built with HTML strings like "<i>Yay</i>" which draws Yay as italic
text. In this example, the "i" tag makes <i> and </i> which surround the word "Yay".
Given tag and word strings, create the HTML string with tags around the word, e.g.
"<i>Yay</i>".
make_tags('i', 'Yay') → '<i>Yay</i>'
make_tags('i', 'Hello') → '<i>Hello</i>'
make_tags('cite', 'Yay') → '<cite>Yay</cite>'
2
CodingBat String 1 - Python
make_out_word
Given an "out" string length 4, such as "<<>>", and a word, return a new string
where the word is in the middle of the out string, e.g. "<<word>>".
make_out_word('<<>>', 'Yay') → '<<Yay>>'
make_out_word('<<>>', 'WooHoo') → '<<WooHoo>>'
make_out_word('[[]]', 'word') → '[[word]]'
extra_end
Given a string, return a new string made of 3 copies of the last 2 chars of the
original string. The string length will be at least 2.
extra_end('Hello') → 'lololo'
extra_end('ab') → 'ababab'
extra_end('Hi') → 'HiHiHi'
first_two
Given a string, return the string made of its first two chars, so the String
"Hello" yields "He". If the string is shorter than length 2, return whatever there is, so
"X" yields "X", and the empty string "" yields the empty string "".
first_two('Hello') → 'He'
first_two('abcdefg') → 'ab'
first_two('ab') → 'ab'
3
CodingBat String 1 - Python
first_half
Given a string of even length, return the first half. So the string "WooHoo"
yields "Woo".
first_half('WooHoo') → 'Woo'
first_half('HelloThere') → 'Hello'
first_half('abcdef') → 'abc'
without_end
Given a string, return a version without the first and last char, so "Hello" yields
"ell". The string length will be at least 2.
without_end('Hello') → 'ell'
without_end('java') → 'av'
without_end('coding') → 'odin'
combo_string
Given 2 strings, a and b, return a string of the form short+long+short, with the
shorter string on the outside and the longer string on the inside. The strings will not
be the same length, but they may be empty (length 0).
combo_string('Hello', 'hi') → 'hiHellohi'
combo_string('hi', 'Hello') → 'hiHellohi'
combo_string('aaa', 'b') → 'baaab'
4
CodingBat String 1 - Python
non_start
Given 2 strings, return their concatenation, except omit the first char of each.
The strings will be at least length 1.
non_start('Hello', 'There') → 'ellohere'
non_start('java', 'code') → 'avaode'
non_start('shotl', 'java') → 'hotlava'
left2
Given a string, return a "rotated left 2" version where the first 2 chars are
moved to the end. The string length will be at least 2.
left2('Hello') → 'lloHe'
left2('java') → 'vaja'
left2('Hi') → 'Hi'
5
CodingBat String 1 - Python
Solutions
hello_name
def hello_name(name):
word = “Hello”
word = word + name + “!”
return word
make_abba
def make_abba(a,b):
return a + b + b + a
make_tags
def make_tags(tag,word):
word1 = “<” + tag + “>”
word2 = word
word3 = “</” + tag + “/>”
finalW = word1 + word2 + word3
return finalW
make_out_word
def make_out_word(out,word):
size = len(out)//2
pal = out[0:size] + word + out[size:]
return pal
6
CodingBat String 1 - Python
extra_end
def extra_end(str):
syl = len(str) - 2
word =3 * str[syl:]
return word
first_two
def first_two(str):
if len(str) < 2:
return str
else:
return str[0:2]
first_half
def first_half(str):
size = len(str) / 2
word = “”
word = str[0:size]
return word
without_end
def without_end(str):
word = str[1:len(str)-1]
return word
7
CodingBat String 1 - Python
combo_string
def combo_string(str):
if len(a) > len(b):
long = a
short = b
else:
long = b
short = a
word = short + long + short
return word
non_start
def non_start(a,b):
word1 = a[1: ]
word1 = b[1: ]
fWord = word1 + word2
return fWord
left2
def left2(str):
syl = str[0:2]
word = str[2: ] + syl
return fWord
8
CodingBat Logic 1 - Python
Questions
cigar_party
When squirrels get together for a party, they like to have cigars. A squirrel
party is successful when the number of cigars is between 40 and 60, inclusive. Unless
it is the weekend, in which case there is no upper bound on the number of cigars.
Return True if the party with the given values is successful, or False otherwise.
cigar_party(30, False) → False
cigar_party(50, False) → True
cigar_party(70, True) → True
date_fashion
You and your date are trying to get a table at a restaurant. The parameter
"you" is the stylishness of your clothes, in the range 0..10, and "date" is the stylishness
of your date's clothes. The result getting the table is encoded as an int value with
0=no, 1=maybe, 2=yes. If either of you is very stylish, 8 or more, then the result is 2
(yes). With the exception that if either of you has style of 2 or less, then the result is
0 (no). Otherwise, the result is 1 (maybe).
date_fashion(5, 10) → 2
date_fashion(5, 2) → 0
date_fashion(5, 5) → 1
squirrel_play
2
CodingBat Logic 1 - Python
The squirrels in Palo Alto spend most of the day playing. In particular, they
play if the temperature is between 60 and 90 (inclusive). Unless it is summer, then
the upper limit is 100 instead of 90. Given an int temperature and a boolean
is_summer, return True if the squirrels play and False otherwise.
squirrel_play(70, False) → True
squirrel_play(95, False) → False
squirrel_play(95, True) → True
caught_speeding
You are driving a little too fast, and a police officer stops you. Write code to
compute the result, encoded as an int value: 0=no ticket, 1=small ticket, 2=big ticket.
If speed is 60 or less, the result is 0. If speed is between 61 and 80 inclusive, the result
is 1. If speed is 81 or more, the result is 2. Unless it is your birthday -- on that day,
your speed can be 5 higher in all cases.
caught_speeding(60, False) → 0
caught_speeding(65, False) → 1
caught_speeding(65, True) → 0
sorta_sum
Given 2 ints, a and b, return their sum. However, sums in the range 10..19
inclusive, are forbidden, so in that case just return 20.
sorta_sum(3, 4) → 7
sorta_sum(9, 4) → 20
sorta_sum(10, 11) → 21
alarm_clock
3
CodingBat Logic 1 - Python
Given a day of the week encoded as 0=Sun, 1=Mon, 2=Tue, ...6=Sat, and a boolean
indicating if we are on vacation, return a string of the form "7:00" indicating when the
alarm clock should ring. Weekdays, the alarm should be "7:00" and on the weekend
it should be "10:00". Unless we are on vacation -- then on weekdays it should be
"10:00" and weekends it should be "off".
alarm_clock(1, False) → '7:00'
alarm_clock(5, False) → '7:00'
alarm_clock(0, False) → '10:00'
love6
The number 6 is a truly great number. Given two int values, a and b, return
True if either one is 6. Or if their sum or difference is 6. Note: the function abs(num)
computes the absolute value of a number.
love6(6, 4) → True
love6(4, 5) → False
love6(1, 5) → True
in1to10
Given a number n, return True if n is in the range 1..10, inclusive. Unless
outside_mode is True, in which case return True if the number is less or equal to 1, or
greater or equal to 10.
in1to10(5, False) → True
in1to10(11, False) → False
in1to10(11, True) → True
near_ten
4
CodingBat Logic 1 - Python
Given a non-negative number "num", return True if num is within 2 of a
multiple of 10.
Note: (a % b) is the remainder of dividing a by b, so (7 % 5) is 2.
near_ten(12) → True
near_ten(17) → False
near_ten(19) → True
Solutions
5
CodingBat Logic 1 - Python
cigar_party
def cigar_party(cigars, is_weekend):
if is_weekend == True:
return cigars >= 40
else:
return cigars >= 40 and cigars <= 60
date_fashion
def date_fashion(you, date):
if you <= 2 or date <= 2:
return 0
elif you >= 8 or date >= 8:
return 2
else:
return 1
squirrel_play
def squirrel_play(temp, is_summer):
if temp >= 60:
if is_summer:
if temp <= 100:
return True
else:
return False
else:
6
CodingBat Logic 1 - Python
if temp <= 90:
return True
else:
return False
else:
return False
caught_speeding
def caught_speeding(speed, is_birthday):
if is_birthday:
speed -= 5
if speed <= 60:
return 0
return 1 if 61 <= speed <= 80 else 2
sorta_sum
def sorta_sum(a, b):
sum = a + b
if 10 <= sum <= 19:
return 20
else:
return sum
alarm_clock
7
CodingBat Logic 1 - Python
def alarm_clock(day, vacation):
week_day = day not in (0, 6)
if vacation:
if week_day:
return '10:00'
else:
return 'off'
else:
if week_day:
return '7:00'
else:
return '10:00'
love6
def love6(a, b):
if (a == 6 or b == 6 or (a+b) == 6 or abs(a-b) == 6):
return True
else:
return False
in1to10
def in1to10(n, outside_mode):
if outside_mode:
return n <= 1 or n >= 10
return 1 <= n <= 10
near_ten
8
CodingBat Logic 1 - Python
def near_ten(num):
num_mod_10 = num % 10
return num_mod_10 <= 2 or num_mod_10 >= 8
9
CodingBat List 1 - Python
Questions
first_last6
Given an array of ints, return True if 6 appears as either the first or last
element in the array. The array will be length 1 or more.
first_last6([1, 2, 6]) → True
first_last6([6, 1, 2, 3]) → True
first_last6([13, 6, 1, 2, 3]) → False
same_first_last
Given an array of ints, return True if the array is length 1 or more, and the first
element and the last element are equal.
same_first_last([1, 2, 3]) → False
same_first_last([1, 2, 3, 1]) → True
same_first_last([1, 2, 1]) → True
make_pi
Return an int array length 3 containing the first 3 digits of pi, {3, 1, 4}.
make_pi() → [3, 1, 4]
common_end
Given 2 arrays of ints, a and b, return True if they have the same first element
or they have the same last element. Both arrays will be length 1 or more.
common_end([1, 2, 3], [7, 3]) → True
common_end([1, 2, 3], [7, 3, 2]) → False
common_end([1, 2, 3], [1, 3]) → True
2
CodingBat List 1 - Python
sum3
Given an array of ints length 3, return the sum of all the elements.
sum3([1, 2, 3]) → 6
sum3([5, 11, 2]) → 18
sum3([7, 0, 0]) → 7
rotate_left3
Given an array of ints length 3, return an array with the elements "rotated
left" so {1, 2, 3} yields {2, 3, 1}.
rotate_left3([1, 2, 3]) → [2, 3, 1]
rotate_left3([5, 11, 9]) → [11, 9, 5]
rotate_left3([7, 0, 0]) → [0, 0, 7]
reverse3
Given an array of ints length 3, return a new array with the elements in
reverse order, so {1, 2, 3} becomes {3, 2, 1}.
reverse3([1, 2, 3]) → [3, 2, 1]
reverse3([5, 11, 9]) → [9, 11, 5]
reverse3([7, 0, 0]) → [0, 0, 7]
3
CodingBat List 1 - Python
max_end3
Given an array of ints length 3, figure out which is larger, the first or last
element in the array, and set all the other elements to be that value. Return the
changed array.
max_end3([1, 2, 3]) → [3, 3, 3]
max_end3([11, 5, 9]) → [11, 11, 11]
max_end3([2, 11, 3]) → [3, 3, 3]
sum2
Given an array of ints, return the sum of the first 2 elements in the array. If
the array length is less than 2, just sum up the elements that exist, returning 0 if the
array is length 0.
sum2([1, 2, 3]) → 3
sum2([1, 1]) → 2
sum2([1, 1, 1, 1]) → 2
middle_way
Given 2 int arrays, a and b, each length 3, return a new array length 2
containing their middle elements.
middle_way([1, 2, 3], [4, 5, 6]) → [2, 5]
middle_way([7, 7, 7], [3, 8, 0]) → [7, 8]
middle_way([5, 2, 9], [1, 4, 5]) → [2, 4]
4
CodingBat List 1 - Python
make_ends
Given an array of ints, return a new array length 2 containing the first and last
elements from the original array. The original array will be length 1 or more.
make_ends([1, 2, 3]) → [1, 3]
make_ends([1, 2, 3, 4]) → [1, 4]
make_ends([7, 4, 6, 2]) → [7, 2]
has23
Given an int array length 2, return True if it contains a 2 or a 3.
has23([2, 5]) → True
has23([4, 3]) → True
has23([4, 5]) → False
5
CodingBat List 1 - Python
Solutions
first_last6
def first_last6(nums):
if nums[0] == 6 or nums[len(nums)-1] == 6:
return True
else:
return False
same_first_last
def same_first_last(nums):
if len(nums) >= 1 and nums[0] == nums[-1]:
return True
else:
return False
make_pi
def make_pi():
return [3,1,4]
common_end
def common_end(a,b):
if a[0] == b[0] or a[len(a) - 1] == b[len(b) - 1]:
return True
else:
return False
6
CodingBat List 1 - Python
sum3
def sum3(nums):
return nums[0] + nums[1] + nums[2]
rotate_left3
def rotate_left3(nums):
return [nums[1], nums[len(nums)-1], nums[0]]
reverse3
def reverse3(nums):
return [nums[len(nums)-1], nums[1], nums[0]]
max_end3
def max_end3(nums):
if nums[0] > nums[-1]:
return [nums[0], nums[0], nums[0]]
else:
return [nums[-1], nums[-1], nums[-1]]
sum2
def sum2(nums):
if len(nums) == 0:
return 0
elif len(nums) < 2:
return nums[0]
else:
return nums[0] + nums[1]
7
CodingBat List 1 - Python
middle_way
def middle_way(a,b):
return [a[1], b[1]]
make_ends
def make_ends(nums):
return [nums[0], nums[len(nums)-1]]
has23
def has23(a,b):
if (nums[0] == 2 or nums[1] == 2) or (nums[0] == 3 or nums[1] == 3):
return True
else:
return False
8
CodingBat Warmup 2 - Python
Questions
string_times
Given a string and a non-negative int n, return a larger string that is n copies
of the original string.
string_times('Hi', 2) → 'HiHi'
string_times('Hi', 3) → 'HiHiHi'
string_times('Hi', 1) → 'Hi'
front_times
Given a string and a non-negative int n, we'll say that the front of the string is
the first 3 chars, or whatever is there if the string is less than length 3. Return n
copies of the front;
front_times('Chocolate', 2) → 'ChoCho'
front_times('Chocolate', 3) → 'ChoChoCho'
front_times('Abc', 3) → 'AbcAbcAbc'
string_bits
Given a string, return a new string made of every other char starting with the
first, so "Hello" yields "Hlo".
string_bits('Hello') → 'Hlo'
string_bits('Hi') → 'H'
string_bits('Heeololeo') → 'Hello'
2
CodingBat Warmup 2 - Python
string_splosion
Given a non-empty string like "Code" return a string like "CCoCodCode".
string_splosion('Code') → 'CCoCodCode'
string_splosion('abc') → 'aababc'
string_splosion('ab') → 'aab'
last2
Given a string, return the count of the number of times that a substring length
2 appears in the string and also as the last 2 chars of the string, so "hixxxhi" yields 1
(we won't count the end substring).
last2('hixxhi') → 1
last2('xaxxaxaxx') → 1
last2('axxxaaxx') → 2
array_count9
Given an array of ints, return the number of 9's in the array.
array_count9([1, 2, 9]) → 1
array_count9([1, 9, 9]) → 2
array_count9([1, 9, 9, 3, 9]) → 3
3
CodingBat Warmup 2 - Python
array_front9
Given an array of ints, return True if one of the first 4 elements in the array is
a 9. The array length may be less than 4.
array_front9([1, 2, 9, 3, 4]) → True
array_front9([1, 2, 3, 4, 9]) → False
array_front9([1, 2, 3, 4, 5]) → False
array123
Given an array of ints, return True if the sequence of numbers 1, 2, 3 appears
in the array somewhere.
array123([1, 1, 2, 3, 1]) → True
array123([1, 1, 2, 4, 1]) → False
array123([1, 1, 2, 1, 2, 3]) → True
string_match
Given 2 strings, a and b, return the number of the positions where they contain
the same length 2 substring. So "xxcaazz" and "xxbaaz" yields 3, since the "xx", "aa",
and "az" substrings appear in the same place in both strings.
string_match('xxcaazz', 'xxbaaz') → 3
string_match('abc', 'abc') → 2
string_match('abc', 'axc') → 0
4
CodingBat Warmup 2 - Python
Solutions
string_times
def string_times(str,n):
return n * str
front_times
def front_times(str,n):
if len(str) < 3:
return n * str
else:
return n * str[0:3]
string_bits
def string_bits(str):
word = “”
for i in range(len(str)):
if i % 2 == 0:
word += str[i:i+1]
return word
string_splosion
def string_splosion(str):
word = “”
for i in range(1, len(str)+1):
word += str[0:i]
return word
5
CodingBat Warmup 2 - Python
last2
def last2(str):
word = “”
count = 0
for i in range(len(str)-2):
if str[i:i+2] == word
count += 1
return count
array_count9
def array_count9(nums):
count = 0
for i in nums:
if i == 9:
return count
array_front9
def array_front9(nums):
end = len(nums)
if end > 4:
end = 4
for i in range(end):
if nums[i] == 9:
return True
return False
6
CodingBat Warmup 2 - Python
array123
def array123(nums):
for i in range(len(nums)-2):
if nums[i] == 1 and nums[i+1] == 2 and nums[i+2] == 3:
return True
return False
string_match
def string_match(a,b):
count = 0
for i in range(len(a)-1):
if a[i:i+2] == b[i:i+2]:
count += 1
return count
7
CodingBat String 2 - Python
Questions
double_char
Given a string, return a string where for every char in the original, there are
two chars.
double_char('The') → 'TThhee'
double_char('AAbb') → 'AAAAbbbb'
double_char('Hi-There') → 'HHii--TThheerree'
count_hi
Return the number of times that the string "hi" appears anywhere in the given
string.
count_hi('abc hi ho') → 1
count_hi('ABChi hi') → 2
count_hi('hihi') → 2
cat_dog
Return True if the string "cat" and "dog" appear the same number of times in
the given string.
cat_dog('catdog') → True
cat_dog('catcat') → False
cat_dog('1cat1cadodog') → True
count_code
2
CodingBat String 2 - Python
Return the number of times that the string "code" appears anywhere in the
given string, except we'll accept any letter for the 'd', so "cope" and "cooe" count.
count_code('aaacodebbb') → 1
count_code('codexxcode') → 2
count_code('cozexxcope') → 2
end_other
Given two strings, return True if either of the strings appears at the very end
of the other string, ignoring upper/lower case differences (in other words, the
computation should not be "case sensitive"). Note: s.lower() returns the lowercase
version of a string.
end_other('Hiabc', 'abc') → True
end_other('AbC', 'HiaBc') → True
end_other('abc', 'abXabc') → True
xyz_there
Return True if the given string contains an appearance of "xyz" where the xyz
is not directly preceeded by a period (.). So "xxyz" counts but "x.xyz" does not.
xyz_there('abcxyz') → True
xyz_there('abc.xyz') → False
xyz_there('xyz.abc') → True
Solutions
3
CodingBat String 2 - Python
double_char
def double_char(str):
word = ""
for i in str:
word += i + i
return word
count_hi
def count_hi(str):
count = 0
for i in range(len(str)-1):
if str[i:i+2] == "hi":
count+=1
return count
cat_dog
def cat_dog(str):
countCat = 0
countDog = 0
for i in range(len(str)-2):
if(str[i:i+3] =="cat"):
countCat+=1
if(str[i:i+3] =="dog"):
countDog+=1
return (countCat == countDog)
count_code
4
CodingBat String 2 - Python
def count_code(str):
count = 0
if(len(str)<4):
return 0
else:
for i in range(len(str)-3):
if(str[i:i+1] == "c" and str[i+1:i+2] == "o" and str[i+3:i+4] == "e"):
count+=1
return count
end_other
def end_other(a, b):
word1 = a.lower()
word2 = b.lower()
if(len(word1)<len(word2)):
small = word1
big = word2
else:
small = word2
big = word1
if(big[len(big)-len(small):] == small):
return True
else:
return False
xyz_there
5
CodingBat String 2 - Python
def xyz_there(str):
word = "xyz"
for i in range(len(str)-2):
if (str[i:i+3] == word and str[i-1:i] != "."):
return True
return False
6
CodingBat Lists 2 - Python
Questions
count_evens
Return the number of even ints in the given array. Note: the % "mod" operator
computes the remainder, e.g. 5 % 2 is 1.
count_evens([2, 1, 2, 3, 4]) → 3
count_evens([2, 2, 0]) → 3
count_evens([1, 3, 5]) → 0
big_diff
Given an array length 1 or more of ints, return the difference between the
largest and smallest values in the array. Note: the built-in min(v1, v2) and max(v1, v2)
functions return the smaller or larger of two values.
big_diff([10, 3, 5, 6]) → 7
big_diff([7, 2, 10, 9]) → 8
big_diff([2, 10, 7, 2]) → 8
centered_average
Return the "centered" average of an array of ints, which we'll say is the mean
average of the values, except ignoring the largest and smallest values in the array.
If there are multiple copies of the smallest value, ignore just one copy, and likewise
for the largest value. Use int division to produce the final average. You may assume
that the array is length 3 or more.
centered_average([1, 2, 3, 4, 100]) → 3
centered_average([1, 1, 5, 5, 10, 8, 7]) → 5
centered_average([-10, -4, -2, -4, -2, 0]) → -3
sum13
2
CodingBat Lists 2 - Python
Return the sum of the numbers in the array, returning 0 for an empty array.
Except the number 13 is very unlucky, so it does not count and numbers that come
immediately after a 13 also do not count.
sum13([1, 2, 2, 1]) → 6
sum13([1, 1]) → 2
sum13([1, 2, 2, 1, 13]) → 6
sum67
Return the sum of the numbers in the array, except ignore sections of
numbers starting with a 6 and extending to the next 7 (every 6 will be followed by at
least one 7). Return 0 for no numbers.
sum67([1, 2, 2]) → 5
sum67([1, 2, 2, 6, 99, 99, 7]) → 5
sum67([1, 1, 6, 7, 2]) → 4
has22
Given an array of ints, return True if the array contains a 2 next to a 2
somewhere.
has22([1, 2, 2]) → True
has22([1, 2, 1, 2]) → False
has22([2, 1, 2]) → False
3
CodingBat Lists 2 - Python
Solutions
count_evens
def count_evens(nums):
count = 0
for i in range(len(nums)):
if nums[i] % 2 == 0:
count += 1
return count
bid_diff
def big_diff(nums):
return max(nums) - min(nums)
centered_average
def centered_average(nums):
nums.sort()
count = 0
total = 0
for i in range(1, len(nums) - 1):
count += 1
total += nums[i]
return total / count
4
CodingBat Lists 2 - Python
sum13
def sum13(nums):
total = 0
skip = False
if len(nums) == 0:
return 0
else:
for i in range(len(nums)):
if nums[i] == 13:
skip = True
elif skip:
skip = False
else:
total += nums[i]
return total
sum67
def sum67(nums):
total = 0
skip = False
for i in range(len(nums)):
if nums[i] == 6:
skip = True
elif nums[i] == 7 and skip:
skip = False
5
CodingBat Lists 2 - Python
elif not skip:
total += nums[i]
return total
has22
def has22(nums):
has2 = False
for i in range(len(nums)):
if has2 and nums[i] == 2:
return True
elif nums[i] == 2:
has2 = True
else:
has2 = False
return False
6
CodingBat Logic 2 - Python
Questions
make_bricks
We want to make a row of bricks that is goal inches long. We have a number
of small bricks (1 inch each) and big bricks (5 inches each). Return True if it is possible
to make the goal by choosing from the given bricks. This is a little harder than it looks
and can be done without any loops.
make_bricks(3, 1, 8) → True
make_bricks(3, 1, 9) → False
make_bricks(3, 2, 10) → True
lone_sum
Given 3 int values, a b c, return their sum. However, if one of the values is the
same as another of the values, it does not count towards the sum.
lone_sum(1, 2, 3) → 6
lone_sum(3, 2, 3) → 2
lone_sum(3, 3, 3) → 0
lucky_sum
Given 3 int values, a b c, return their sum. However, if one of the values is 13
then it does not count towards the sum and values to its right do not count. So for
example, if b is 13, then both b and c do not count.
lucky_sum(1, 2, 3) → 6
lucky_sum(1, 2, 13) → 3
lucky_sum(1, 13, 3) → 1
2
CodingBat Logic 2 - Python
no_teen_sum
Given 3 int values, a b c, return their sum. However, if any of the values is a
teen -- in the range 13..19 inclusive -- then that value counts as 0, except 15 and 16
do not count as a teens. Write a separate helper "def fix_teen(n):"that takes in an int
value and returns that value fixed for the teen rule. In this way, you avoid repeating
the teen code 3 times (i.e. "decomposition"). Define the helper below and at the same
indent level as the main no_teen_sum().
no_teen_sum(1, 2, 3) → 6
no_teen_sum(2, 13, 1) → 3
no_teen_sum(2, 1, 14) → 3
round_sum
For this problem, we'll round an int value up to the next multiple of 10 if its
rightmost digit is 5 or more, so 15 rounds up to 20. Alternately, round down to the
previous multiple of 10 if its rightmost digit is less than 5, so 12 rounds down to 10.
Given 3 ints, a b c, return the sum of their rounded values. To avoid code repetition,
write a separate helper "def round10(num):" and call it 3 times. Write the helper
entirely below and at the same indent level as round_sum().
round_sum(16, 17, 18) → 60
round_sum(12, 13, 14) → 30
round_sum(6, 4, 4) → 10
3
CodingBat Logic 2 - Python
close_far
Given three ints, a b c, return True if one of b or c is "close" (differing from a
by at most 1), while the other is "far", differing from both other values by 2 or more.
Note: abs(num) computes the absolute value of a number.
close_far(1, 2, 10) → True
close_far(1, 2, 3) → False
close_far(4, 1, 3) → True
make_chocolate
We want make a package of goal kilos of chocolate. We have small bars (1 kilo
each) and big bars (5 kilos each). Return the number of small bars to use, assuming
we always use big bars before small bars. Return -1 if it can't be done.
make_chocolate(4, 1, 9) → 4
make_chocolate(4, 1, 10) → -1
make_chocolate(4, 1, 7) → 2
4
CodingBat Logic 2 - Python
Solutions
make_bricks
def make_bricks(small, big, goal):
big_needed = min(big, goal // 5)
return goal - (big_needed * 5) <= small
lone_sum
def lone_sum(a, b, c):
sum = 0
if a not in [b,c]:
sum += a
if b not in [a,c]:
sum += b
if c not in [a,b]:
sum += c
return sum
lucky_sum
def lucky_sum(a, b, c):
sum = 0
for n in (a, b, c):
if n != 13:
sum += n
else:
break
return sum
5
CodingBat Logic 2 - Python
no_teen_sum
def no_teen_sum(a, b, c):
nums = (a, b, c)
sum = 0
for i in range(len(nums)):
sum += fix_teen(nums[i])
return sum
def fix_teen(n):
if n != 15 and n!= 16 and 13 <= n <= 19:
return 0
else:
return n
round_sum
def round_sum(a, b, c):
return round10(a)+round10(b)+round10(c)
def round10(num):
return (num+5)/10*10
6
CodingBat Logic 2 - Python
close_far
def close_far(a, b, c):
ab_diff = abs(a - b)
ac_diff = abs(a - c)
bc_diff = abs(b - c)
if (ab_diff <= 1 and ac_diff >= 2 and bc_diff >= 2) != (ac_diff <= 1 and ab_diff >= 2 and
bc_diff >= 2):
return True
else:
return False
make_chocolate
def make_chocolate(small, big, goal):
if goal >= 5 * big:
remainder = goal - 5 * big
else:
remainder = goal % 5
if remainder <= small:
return remainder
return -1
7
19 Problems of Python Advanced
Questions
Problem 0
Ask a user for his name. Print it using f-strings:
https://www.geeksforgeeks.org/formatted-string-literals-f-strings-python/
Problem 1
Create and print a dictionary.
Problem 2
Create a dictionary. Print its keys and values without a loop.
Problem 3
Create a dictionary. Loop over its keys and values using the .items() function.
Problem 4
Create a dictionary. Print the value of a particular key.
Problem 5
Create a dictionary. Add a key and value to the dictionary. Print the result.
Problem 6
Create a list of strings that contains the name Rodrigo. Check if Rodrigo is in
the list. If he is, print Found, otherwise Not Found. Use the function in.
Problem 7
Create a dictionary with names and phone numbers. Ask user for a name. If
name in the dictionary, print their phone number.
2
19 Problems of Python Advanced
Problem 8
Create a list of dictionaries. Print it.
Problem 9
Create a dictionary where the keys are numbers between 1 and 15 (both
included) and the values are square of keys. Print the dictionary.
Problem 10
Call the program from the terminal with arguments. Print the arguments.
Problem 11
Call the program from the terminal with arguments. Print “Hello, world” if
there are arguments. Else, print “Hello” with the value of the argument.
Problem 12
Create a file called days.txt with days of the week, one at each line. Open the
file and read its content.
days.txt file:
January
Problem 13
Create a file called days.txt with days of the week, one at each line. Open the
file and read the first line.
days.txt file:
January
3
19 Problems of Python Advanced
Problem 14
Create a file called numbers.txt. Write numbers 1 to 100, at each line.
Example of numbers.txt file:
1
2
3
...
99
100
Problem 15
Open the file numbers.txt and read the first line. Use with open() as syntax.
Problem 16
Create a spreadsheet file and put 10 of your favorite desserts in the first
column. Download file with .csv extension. Open CSV file. Print the elements of the
file.
Example of desserts.csv file:
cheesecake
cookie
ice-cream
...
tiramisu
chocolate
4
19 Problems of Python Advanced
Problem 17
Create a spreadsheet file and put 10 of your favorite desserts in the first
column (with some repetitive ones). Download file with .csv extension. Open CSV file.
Count the number of desserts, put result in a dictionary and print it.
Problem 18
Create a spreadsheet file and put 10 of your favorite desserts in the first
column (with some repetitive ones). In the first row of the column put the title of the
column as dessert. Download file with .csv extension. Open CSV file. Print each
dessert using the name of the column.
5
19 Problems of Python Advanced
Solutions
Problem 0
answer = input("What's your name? ")
print(f"hello, {answer}")
Problem 1
thisdict = {
"brand": "Ford",
"model": "Mustang",
"year": 1964
}
print(thisdict)
Problem 2
car = {
"brand": "Ford",
"model": "Mustang",
"year": 1964
}
print(car.values())
print(car.keys())
6
19 Problems of Python Advanced
Problem 3
thisdict = {
"brand": "Ford",
"model": "Mustang",
"year": 1964
}
for x, y in thisdict.items():
print(x, y)
Problem 4
thisdict = {
"brand": "Ford",
"model": "Mustang",
"year": 1964
}
print(thisdict["model"])
print(thisdict["year"])
Problem 5
thisdict = {
"brand": "Ford",
"model": "Mustang",
"year": 1964
}
thisdict["color"] = "red"
print(thisdict)
7
19 Problems of Python Advanced
Problem 6
names = ["Bill", "Charlie", "Fred", "George", "Ginny", "Percy", "Rodrigo"]
if "Rodrigo" in names:
print("Found")
else:
print("Not found")
Problem 7
people = {
"Brian": "+1-617-495-1000",
"David": "+1-949-468-2750"
}
name = input("Name: ")
if name in people:
print(f"Number: {people[name]}")
Problem 8
person1 = {
"name": "Rodrigo",
"age": 28
}
person2 = {
"name": "Giovanna",
"age": 22
}
l = [person1, person2]
print(l)
8
19 Problems of Python Advanced
Problem 9
d=dict()
for x in range(1,16):
d[x]=x**2
print(d)
Problem 10
from sys import argv
for arg in argv:
print(arg)
print(len(argv))
Problem 11
from sys import argv
if len(argv) == 2:
print(f"hello, {argv[1]}")
else:
print("hello, world")
Problem 12
days_file = open('days.txt','r')
print(days_file.read())
days_file.close()
9
19 Problems of Python Advanced
Problem 13
days_file = open('days.txt','r')
print(days_file.readline(), end="")
days_file.close()
Problem 14
num_files = open('numbers.txt','w')
for i in range(1, 101):
num_files.write(f"{str(i)}\n")
num_files.close()
Problem 15
with open("numbers.txt", "r") as file:
print(file.readline())
Problem 16
import csv
with open("desserts.csv", "r") as file:
reader = csv.reader(file)
for row in reader:
print(row[0])
10
19 Problems of Python Advanced
Problem 17
import csv
desserts_count = dict()
with open("desserts.csv", "r") as file:
reader = csv.reader(file)
for row in reader:
current_dessert = row[0]
if current_dessert in desserts_count:
desserts_count[current_dessert] += 1
else:
desserts_count[current_dessert] = 1
print(desserts_count)
Problem 18
import csv
desserts_count = dict()
with open("desserts.csv", "r") as file:
reader = csv.DictReader(file)
for row in reader:
print(row['dessert'])
11
SQL Boat
Questions
Lesson 1: SELECT queries 101
1.
2.
3.
4.
5.
Find the title of each film
Find the director of each film
Find the title and director of each film
Find the title and year of each film
Find all the information about each film
Lesson 2: Queries with constraints (Pt. 1)
1.
2.
3.
4.
Find the movie with a row id of 6
Find the movies released in the years between 2000 and 2010
Find the movies not released in the years between 2000 and 2010
Find the first 5 Pixar movies and their release year
Lesson 3: Queries with constraints (Pt. 2)
1.
2.
3.
4.
Find all the Toy Story movies
Find all the movies directed by John Lasseter
Find all the movies (and director) not directed by John Lasseter
Find all the WALL-* movies
Lesson 4: Filtering and sorting Query results
1.
2.
3.
4.
List all directors of Pixar movies (alphabetically), without duplicates
List the last four Pixar movies released (ordered from most recent to least)
List the first five Pixar movies sorted alphabetically
List the next five Pixar movies sorted alphabetically
Review: Simple SELECT Queries
1.
2.
3.
4.
5.
List all the Canadian cities and their populations
Order all the cities in the United States by their latitude from north to south
List all the cities west of Chicago, ordered from west to east
List the two largest cities in Mexico (by population)
List the third and fourth largest cities (by population) in the United States and
their population
2
SQL Boat
Lesson 6: Multi-table queries with JOINs
1. Find the domestic and international sales for each movie
2. Show the sales numbers for each movie that did better internationally rather
than domestically
3. List all the movies by their ratings in descending order
Lesson 7: OUTER JOINs
1. Find the list of all buildings that have employees
2. Find the list of all buildings and their capacity
3. List all buildings and the distinct employee roles in each building (including
empty buildings)
Lesson 8: A short note on NULLs
1. Find the name and role of all employees who have not been assigned to a
building
2. Find the names of the buildings that hold no employees
Lesson 9: Queries with expressions
1. List all movies and their combined sales in millions of dollars
2. List all movies and their ratings in percent
3. List all movies that were released on even number years
Lesson 10: Queries with aggregates (Pt. 1)
1. Find the longest time that an employee has been at the studio
2. For each role, find the average number of years employed by employees in
that role
3. Find the total number of employee years worked in each building
Lesson 11: Queries with aggregates (Pt. 2)
1. Find the number of Artists in the studio (without a HAVING clause)
2. Find the number of Employees of each role in the studio
3. Find the total number of years employed by all Engineers
3
SQL Boat
Lesson 12: Order of execution of a Query
1. Find the number of movies each director has directed
2. Find the total domestic and international sales that can be attributed to each
director
Lesson 13: Inserting rows
1. Add the studio's new production, Toy Story 4 to the list of movies (you can use
any director)
2. Toy Story 4 has been released to critical acclaim! It had a rating of 8.7, and
made 340 million domestically and 270 million internationally. Add the record
to the BoxOffice table.
Lesson 14: Updating rows
1. The director for A Bug's Life is incorrect, it was actually directed by John
Lasseter
2. The year that Toy Story 2 was released is incorrect, it was actually released
in 1999
3. Both the title and director for Toy Story 8 is incorrect! The title should be "Toy
Story 3" and it was directed by Lee Unkrich
Lesson 15: Deleting rows
1. This database is getting too big, lets remove all movies that were released
before 2005.
2. Andrew Stanton has also left the studio, so please remove all movies directed
by him.
Lesson 16: Creating tables
Create a new table named Database with the following columns:
– Name A string (text) describing the name of the database
– Version A number (floating point) of the latest version of this database
– Download_count An integer count of the number of times this database was
downloaded
4
SQL Boat
Lesson 17: Altering tables
1. Add a column named Aspect_ratio with a FLOAT data type to store the aspectratio each movie was released in.
2. Add another column named Language with a TEXT data type to store the
language that the movie was released in. Ensure that the default for this
language is English.
Lesson 18: Dropping tables
1. We've sadly reached the end of our lessons, lets clean up by removing the
Movies table
2. And drop the BoxOffice table as well
5
SQL Boat
Solutions
Lesson 1: SELECT queries 101
1. SELECT title
FROM movies;
2. SELECT director
FROM movies;
3. SELECT title, director
FROM movies;
4. SELECT title, year
FROM movies;
5. SELECT *
FROM movies;
Lesson 2: Queries with constraints (Pt. 1)
1. SELECT *
FROM movies
WHERE id = 6;
2. SELECT *
FROM movies
WHERE year BETWEEN 2000 and 2010;
6
SQL Boat
3. SELECT *
FROM movies
WHERE year NOT BETWEEN 2000 and 2010;
4. SELECT *
FROM movies
WHERE id BETWEEN 1 AND 5;
Lesson 3: Queries with constraints (Pt. 2)
1. SELECT *
FROM movies
WHERE title LIKE "%Toy Story%";
2. SELECT *
FROM movies
WHERE director = "John Lasseter";
3. SELECT *
FROM movies
WHERE director != "John Lasseter";
4. SELECT *
FROM movies
WHERE title LIKE "WALL-%";
7
SQL Boat
Lesson 4: Filtering and sorting Query results
1. SELECT DISTINCT director
FROM movies
ORDER BY director ASC;
2. SELECT *
FROM movies
ORDER BY year DESC
LIMIT 4;
3. SELECT *
FROM movies
ORDER BY title ASC
LIMIT 5;
4. SELECT *
FROM movies
ORDER BY title ASC
LIMIT 5
OFFSET 5;
Lesson 5 Review: Simple SELECT Queries
1. SELECT country, population
FROM north_american_cities
WHERE country = "Canada";
8
SQL Boat
2. SELECT city
FROM north_american_cities
WHERE country = "United States"
ORDER BY latitude DESC;
3. SELECT city
FROM north_american_cities
WHERE longitude < (
SELECT longitude
FROM north_american_cities
WHERE city = "Chicago"
)
ORDER BY longitude ASC;
4. SELECT city
FROM north_american_cities
WHERE country = "Mexico"
ORDER BY population DESC
LIMIT 2;
5. SELECT city, population
FROM north_american_cities
WHERE country = "United States"
ORDER BY population DESC
LIMIT 2
OFFSET 2;
9
SQL Boat
Lesson 6: Multi-table queries with JOINs
1. SELECT title, domestic_sales, international_sales
FROM movies
INNER JOIN boxoffice
ON movies.id = boxoffice.movie_id;
2. SELECT *
FROM movies
INNER JOIN boxoffice
ON movies.id = boxoffice.movie_id
WHERE international_sales > domestic_sales;
3. SELECT title, rating
FROM movies
INNER JOIN boxoffice
ON movies.id = boxoffice.movie_id
ORDER BY rating DESC;
Lesson 7: OUTER JOINs
1. SELECT DISTINCT building_name
FROM buildings
LEFT JOIN employees
ON buildings.building_name = employees.building
WHERE building IS NOT NULL;
10
SQL Boat
2. SELECT *
FROM buildings;
3. SELECT DISTINCT building_name, role
FROM buildings
LEFT JOIN employees
ON buildings.building_name = employees.building;
Lesson 8: A short note on NULLs
1. SELECT *
FROM employees
LEFT JOIN buildings
ON employees.building = buildings.building_name
WHERE building_name IS NULL;
2. SELECT *
FROM buildings
LEFT JOIN employees
ON buildings.building_name = employees.building
WHERE role IS NULL;
11
SQL Boat
Lesson 9: Queries with expressions
1. SELECT
title,
(domestic_sales + international_sales)/1000000 AS sales
FROM boxoffice AS b
INNER JOIN movies AS m
ON m.id = b.movie_id;
2. SELECT
title,
rating*10 AS ratings_percent
FROM boxoffice AS b
INNER JOIN movies AS m
ON m.id = b.movie_id;
3. SELECT title, year
FROM boxoffice AS b
INNER JOIN movies AS m
ON m.id = b.movie_id
WHERE year % 2 = 0
ORDER BY year ASC;
Lesson 10: Queries with aggregates (Pt. 1)
1. SELECT MAX(years_employed) AS longest_years
FROM employees;
12
SQL Boat
2. SELECT
role,
AVG(years_employed)AS average_years_employed
FROM employees
GROUP BY role;
3. SELECT
building,
SUM(years_employed)AS sum_of_years_employed
FROM employees
GROUP BY building;
Lesson 11: Queries with aggregates (Pt. 2)
1. SELECT COUNT(role)
FROM employees
WHERE role = 'Artist';
2. SELECT
role,
COUNT(name) AS number_of_employees
FROM employees
GROUP BY role;
13
SQL Boat
3. SELECT
role,
SUM(years_employed)
FROM employees
GROUP BY role
HAVING role = "Engineer";
Lesson 12: Order of execution of a Query
1. SELECT
director,
COUNT(*)
FROM movies
GROUP BY director;
1. SELECT
director,
SUM(domestic_sales + international_sales) AS total_sales
FROM movies
INNER JOIN boxoffice
ON movies.id = boxoffice.movie_id
GROUP BY director;
Lesson 13: Inserting rows
1. INSERT INTO movies
(title, director, year, length_minutes)
VALUES
('Toy Story 4', 'Lance Lafontaine', 2984, 15);
14
SQL Boat
2. INSERT INTO boxoffice
(movie_id, rating, domestic_sales, international_sales)
VALUES
(15, 8.7, 340000000, 270000000);
Lesson 14: Updating rows
1. UPDATE movies
SET director = "John Lasseter"
WHERE title = "A Bug's Life";
2. UPDATE movies
SET
title = 'Toy Story 3',
director = 'Lee Unkrich'
WHERE id = (
SELECT id
FROM movies
WHERE title = 'Toy Story 8'
);
Lesson 15: Deleting rows
1. DELETE FROM movies
WHERE year < 2005;
2. DELETE FROM movies
WHERE director = 'Andrew Stanton';
15
SQL Boat
Lesson 16: Creating tables
CREATE TABLE IF NOT EXISTS Database (
Name TEXT,
Version FLOAT,
Download_count INTEGER
);
Lesson 17: Altering tables
1. ALTER TABLE movies
ADD aspect_ratio FLOAT;
2. ALTER TABLE movies
ADD language TEXT
DEFAULT 'English';
Lesson 18: Dropping tables
1. DROP TABLE IF EXISTS movies;
2. DROP TABLE IF EXISTS boxoffice;
16
Build Your First Project - Javascript
styles.css
h1{
text-align: center;
color: #FFD700;
margin-top: 50px;
}
index.html
<!DOCTYPE html>
<html lang="en">
<head>
<script src="index.js"></script>
<link
href="https://cdn.jsdelivr.net/npm/bootstrap@5.0.0beta3/dist/css/bootstrap.min.css"
rel="stylesheet"
integrity="sha384eOJMYsd53ii+scO/bJGFsiCZc+5NDVN2yr8+0RDqr0Ql0h+rP48ckxlpbzKgwra6"
crossorigin="anonymous">
<link href="styles.css" rel="stylesheet">
<title>First Project</title>
</head>
<body>
<div class="d-flex justify-content-center" style="margin-top:50px">
<button id="hello" class="btn btn-warning">Welcome!</button>
<button id="red" class="btn btn-danger">Red</button>
<button id="green" class="btn btn-success">Green</button>
<button id="blue" class="btn btn-primary">Blue</button>
</div>
<h1></h1>
</body>
</html>
2
Build Your First Project - Javascript
index.js
document.addEventListener('DOMContentLoaded', function(){
//Get the parameters in HTML
let sayhello = document.querySelector('h1');
let body = document.querySelector('body');
//Send a "Hello" message when click the button
document.querySelector('#hello').onclick = function() {
sayhello.innerHTML = 'Hello, you!';
body.style.backgroundColor = 'white';
};
//Change the background color to red when click the button
document.querySelector('#red').onclick = function() {
body.style.backgroundColor = 'red';
sayhello.innerHTML = '';
};
//Change the background color to green when click the button
document.querySelector('#green').onclick = function() {
body.style.backgroundColor = 'green';
sayhello.innerHTML = '';
};
//Change the background color to blue when click the button
document.querySelector('#blue').onclick = function() {
body.style.backgroundColor = 'blue';
sayhello.innerHTML = '';
};
});
3
TODO - Flask
application.py
from flask import Flask, redirect, render_template, request
app = Flask(__name__)
#Create this to have a list of todos
todos = []
@app.route("/")
def tasks():
return render_template("tasks.html", todos=todos)
@app.route("/add", methods=["GET","POST"])
def add():
#GET is a request method used by default
#And is used when you want to get a page
if request.method == "GET":
return render_template("add.html")
#POST means you're trying to send data to the server
else:
#Get the input from the user
todo = request.form.get('task')
#Add this new task to the todos list
todos.append(todo)
#Redirect the user to the page that has the todos
return redirect("/")
2
TODO - Flask
layout.html
<!DOCTYPE html>
<html lang="en">
<head>
<title>Tasks</title>
</head>
<body>
{% block body %}
{% endblock %}
</body>
</html>
tasks.html
{% extends "layout.html" %}
{% block body %}
<h1>Tasks</h1>
<ul>
{% for todo in todos %}
<li>{{ todo }}</li>
{% endfor %}
</ul>
<a href="/add">Create a New Task!</a>
{% endblock %}
3
TODO - Flask
add.html
{% extends "layout.html" %}
{% block body %}
<form action="/add" method="POST">
<input id="task" name="task" type="text" placeholder="Add New Task!">
<input id="submit" type="submit" disabled>
</form>
<script>
document.querySelector('#task').onkeyup = function() {
if (document.querySelector('#task').value === ''){
document.querySelector('#submit').disabled = true;
}
else{
document.querySelector('#submit').disabled = false;
}
}
</script>
{% endblock %}
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Checklist – Search (Project 0)
Summary
Pages........................................................................................................................................... 3
Query Text.................................................................................................................................. 4
Query Images............................................................................................................................ 5
Query Advanced....................................................................................................................... 6
Appearance ............................................................................................................................... 8
Lucky ........................................................................................................................................... 9
Aesthetics................................................................................................................................ 10
FAQ.............................................................................................................................................. 11
Important
Throughout this document there will be blue colored links.
These links will help you to solve the project.
Right-click and open in a new tab.
Disclaimer
This is a checklist to help you go through the problem.
The following checklist if for educational purposes only.
Cheating or any other activities are highly discouraged!
2
Checklist – Search (Project 0)
Pages
Specification
Your website should have at least three pages: one for Google Search, one for
Google Image Search, and one for Google Advanced Search.
How To Do This?
Since the project must have three pages and the distribution code already
given to us index.html, you have to create two more HTML files for the Google Image
Search and Google Advanced Search.
Specification
On the Google Search page, there should be links in the upper-right of the
page to go to Image Search or Advanced Search. On each of the other two pages,
there should be a link in the upper-right to go back to Google Search.
How To Do This?
To solve this problem, you can use the <ul> tag to create a navbar. This navbar
must contain 2 nav-item (in this case you can use the <li> tag) to redirect the site to
the other two pages that are not open.
For example, the Google search page must have two nav-item to redirect the
site to Image Search or Advanced Search, like indicated by the green arrows in the
image below.
The best way to do this is using the <a> tag, where the “href” is going to set the
HTML file you want to redirect when the user clicks in the text.
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Checklist – Search (Project 0)
Query Text
Specification
On the Google Search page, the user should be able to type in a query, click
“Google Search”, and be taken to the Google search results for that page.
How To Do This?
The code already gives to us the <form> and the action with the corresponding
page that we are going find the result. We also have the two <input> tags that creates
the text input and the submit button.
Note that in the <input type=”text”> we have a property of name=”q” inside. The
action added with this name are going to redirect the page to the corresponding
result page right after the button submit is clicked. So, in this part you do not need to
do anything, the project already give this to us.
Specification
Like Google’s own, your search bar should be centered with rounded corners.
The search button should also be centered and should be beneath the search bar.
How To Do This?
To do this, it is recommended that you create a CSS file. You can find how to
do rounded corners using the CSS tools in this link:
https://www.w3schools.com/cssref/css3_pr_border-radius.asp
4
Checklist – Search (Project 0)
You can find how to align the elements in the Bootstrap documentation. We
suggest you to use the <input type=”submit”> inside a <div> tag to use the Bootstrap
class. Look on this link:
https://getbootstrap.com/docs/4.0/utilities/flex/
At this point, your project should look like this:
Query Images
Specification
On the Google Image Search page, the user should be able to type in a query,
click a search button, and be taken to the Google Image search results for that page.
How To Do This?
The first thing you have to do is to create a file similar to index.html, but the
difference in this case will be the <a> tag, because you have to redirect to Google
Search and Google Advanced Search.
For the image search you must use de Developer Tools to find how to do this
search. You are going to have to use an <input type=”hidden”> tag.
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Checklist – Search (Project 0)
At this point, your project should look like this:
Query Advanced
On the Google Advanced Search page, the user should be able to provide input
for the following four fields (taken from Google’s own advanced search options).
Specification
Find pages with… “all these words:”
How To Do This?
On Google Advanced Search page, you should use the <input> tag and add the
name property like appears when you check the Developer Tools. The image below
shows the trick:
6
Checklist – Search (Project 0)
Specification
Find pages with… “this exact word or phrase:”
How To Do This?
On Google Advanced Search page, you should use the <input> tag and add the
name property like appears when you check the Developer Tools. The image below
shows the trick:
Specification
Find pages with… “any of these words:”
How To Do This?
On Google Advanced Search page, you should use the <input> tag and add the
name property like appears when you check the Developer Tools. The image below
shows the trick:
Specification
Find pages with… “none of these words:”
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Checklist – Search (Project 0)
How To Do This?
On Google Advanced Search page, you should use the <input> tag and add the
name property like appears when you check the Developer Tools. The image below
shows the trick:
Appearance
Specification
Like Google’s own Advanced Search page, the four options should be stacked
vertically, and all the text fields should be left aligned.
How To Do This?
To stack the four options vertically in the Advanced Search page, you can use
one <div> tag for each input.
To do all the text fields left aligned, you can add in your CSS file a class setting
the margin-left size you want to have in your page.
At this point your project should look like this:
8
Checklist – Search (Project 0)
Specification
Consistent with Google’s own CSS, the “Advanced Search” button should be
blue with white text. When the “Advanced Search” button is clicked, the user should
be taken to search results page for their given query.
How To Do This?
To do this part, you can use the Bootstrap documentation about buttons. Look
on this link:
https://getbootstrap.com/docs/4.0/components/buttons/
Lucky
Specification
Add an “I’m Feeling Lucky” button to the main Google Search page. Consistent
with Google’s own behavior, clicking this link should take users directly to the first
Google search result for the query, bypassing the normal results page.
How To Do This?
On Google Search page, you should use the <input> tag and add the name
property like appears when you check the Developer Tools. The image below shows
the trick:
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Checklist – Search (Project 0)
Aesthetics
Specification
The CSS you write should match Google’s own aesthetics as best as possible.
How To Do This?
We suggest you check the CSS and Bootstrap documentation. Also, use the
Developer Tools to know some interesting properties to be used in your project.
For example, if you want to know the margin, background and padding of the
original “Google Search” button, you can use the Developer Tools to check that.
.
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Checklist – Search (Project 0)
FAQ
Question
Answer
Try searching for "CS50" on Google, then do the same on Google Images and
compare the URLs.
You will see the only difference between them is an additional parameter
called tbm, which Google uses to know it should display the Google Images results
instead of the Search results.
You need to use this parameter in project0 to redirect to the correct results
page.
Question
Answer
To do this you should use margin property of CSS and align elements property,
also from CSS. Check the link below:
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Checklist – Search (Project 0)
https://www.w3schools.com/css/css_align.asp
Question
Answer
We already answer that in the Query Advanced section.
Question
Answer
We already answer that in the Query Advanced section.
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Checklist – Wiki (Project 1)
Summary
Understanding Util.py............................................................................................................. 3
Convert Markdown to HTML................................................................................................. 4
Entry Page ................................................................................................................................. 5
Hint............................................................................................................................................... 7
Index Page................................................................................................................................. 7
Search......................................................................................................................................... 8
New Page................................................................................................................................. 10
Edit Page ...................................................................................................................................13
Random Page...........................................................................................................................16
FAQ..............................................................................................................................................17
Important
Throughout this document there will be blue colored links.
These links will help you to solve the project.
Right-click and open in a new tab.
Disclaimer
This is a checklist to help you go through the problem.
The following checklist if for educational purposes only.
Cheating or any other activities are highly discouraged!
2
Checklist – Wiki (Project 1)
Understanding Util.py
list_entries()
Returns a list of all names of encyclopedia entries.
Let us look on how to use this function:
allEntries = util.list_entries()
Now, let us look on how the information that this function returns come to us
(using the debugger):
save_entry(title,content)
Saves an encyclopedia entry, given its title and Markdown content. If an
existing entry with the same title already exists, it is replaced.
Let us look on how to use this function:
util.save_entry(title,content)
get_entry(title)
Retrieves an encyclopedia entry by its title. If no such entry exists, the function
returns None.
Let us look on how to use this function:
entry = util.get_entry(title)
Now, let us look on how the information that this function returns come to us
(using the debugger):
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Checklist – Wiki (Project 1)
Convert Markdown to HTML
Specification
On each entry’s page, any Markdown content in the entry file should be
converted to HTML before being displayed to the user. You may use the pythonmarkdown2 package to perform this conversion, installable via pip3 install
markdown2.
How To Do This?
First you should understand what the python-markdown2 does. You can check
the link given to us in the specifications:
https://github.com/trentm/python-markdown2
Markdown is a light text markup language, and the entries are written in this
language. The problem of this project is that we are using HTML, that is another
markup language. How to solve this?
The link explains how we are going to do this. But just the link is not enough.
The first thing you must do is to import the markdown2 library in ‘views.py’.
Then, you are going to do this conversion every time you have to display the
page that already exists in the entries folder or every time you create a new page.
First, you are going to create a variable to store the ‘Markdown()’ function. This
function is going to do the conversion to you. For example:
markdown = Markdown()
But how am I going to take the markdown content of the entry?
To do this, you should use the ‘get_entry’ function, because it retrieves an
encyclopedia entry by its title. If no such entry exists, the function returns None.
Thus, you are going to store in a variable the entry using the ‘get_entry’
function. For example:
entry = util.get_entry(entry_name)
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Checklist – Wiki (Project 1)
If the ‘get_entry’ function returns None, you are going to return None in your
conversion.
If the ‘get_entry’ function does not return None, you are going to create a new
variable to store this conversion. In this variable, you are going to use the explanation
in the link. Thus, you are going to do the following.
html_converted = markdown.convert(entry)
It is scary for the first time, but you are going to see that this will save you
time!
Entry Pages
Specification
Visiting /wiki/TITLE, where TITLE is the title of an encyclopedia entry, should
render a page that displays the contents of that encyclopedia entry.
How To Do This?
To solve this, you should go to urls.py file and add in the urlpatters a new path.
Look at Lecture Django in CS50 notes and check the ‘greet’ function. You
should understand the flexible way that they use to create a path (image below):
Thus this new path will be something like ‘/wiki/<str: title>’, where the ‘title’
will the title of an encyclopedia entry.
Specification
The view should get the content of the encyclopedia entry by calling the
appropriate util function.
How To Do This?
To solve this, you should go to views.py file and add a new route.
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Checklist – Wiki (Project 1)
Look at Lecture Django in CS50 notes and check the ‘greet’ function. You
should understand how they use the <str:name> from url in the route (image below):
With the ‘title’ in hands, you can call the appropriate util function.
In the entry page, you want to display the content of the title. You should use
the logic to convert the Mardown to HTML.
Specification
If an entry is requested that does not exist, the user should be presented with
an error page indicating that their requested page was not found.
How To Do This?
Like explained in the previous bullet point, the ‘get_entry’ retrieves an
encyclopedia entry by its title. If no such entry exists, the function returns None. Thus,
your ‘conversion Markdown to HTML’ returns or the HTML content or None.
Knowing that, you should do an if-else condition in your route (views.py file)
using the None as this condition.
If ‘conversion Markdown to HTML’ returns None, you should display a page
indicating that the entry does not exists.
You can create a new HTML file to display just this error message and indicate
in the route to render that specific page.
Specification
If the entry does exist, the user should be presented with a page that displays
the content of the entry. The title of the page should include the name of the entry.
How To Do This?
If ‘conversion Markdown to HTML’ does not return None, you should display
the entry page. To do this, you should pass as context the title and the conversion to
HTML to render the html file.
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Checklist – Wiki (Project 1)
Look at Lecture Django in CS50 notes and check the ‘greet’ function. You
should understand how they pass the context from Django to HTML (image below):
Hint
Specification
By default, when substituting a value in a Django template, Django HTMLescapes the value to avoid outputting unintended HTML. If you want to allow for an
HTML string to be outputted, you can do so with the safe filter (as by adding |safe
after the variable name you’re substituting).
How To Do This?
You probably had this issue when trying to render your entry page. If you do
not use this ‘save’ property in the HTML file, the compiler will understand that you
are passing a string and not a html content.
To solve this, use the value of the conversion to html and the safe word
together. For example:
{{ conversion_html | safe }}
Index Page
Specification
Update index.html such that, instead of merely listing the names of all pages
in the encyclopedia, user can click on any entry name to be taken directly to that
entry page.
How To Do This?
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Checklist – Wiki (Project 1)
To solve this, you should go to ‘index.html’ file and you are going to find
basically all done for you. The only thing that you have to add is an <a> tag to solve
this ‘click on any entry name to be taken directly to that entry page’.
Final Step
You should go to ‘layout.html’ and add <a> tag to the user be able to click in
‘Home’ and go to the index page.
Search
Specification
Allow the user to type a query into the search box in the sidebar to search for
an encyclopedia entry.
How To Do This?
To solve that, you should create a new URL simple path in ‘urls.py’. Like the
following image from Lecture Django in CS50 notes.
In addition, you should create a new route in ‘views.py’. In there, you should
use the ‘list_entries’ function the way that we recommended in the beginning of this
checklist.
Then, you should get the input from the user in the search box and store in a
variable. Since this is a request GET method, you should use, for example:
search = request.GET(‘NameOfTheInputOnHTML’)
To check if there is an entry with the title that the user wants to search, you
should use the ‘get_entry’ function the way that we recommended in the beginning of
this checklist.
Specification
If the query matches the name of an encyclopedia entry, the user should be
redirected to that entry’s page.
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Checklist – Wiki (Project 1)
How To Do This?
This will occur if the function ‘get_entry’ does not return None.
Then, you should render the entry page of this entry searched.
Specification
If the query does not match the name of an encyclopedia entry, the user should
instead be taken to a search results page that displays a list of all encyclopedia
entries that have the query as a substring. For example, if the search query were ‘Py’,
then ‘Python’ should appear in the search results.
How To Do This?
This will occur if the function ‘get_entry’ returns None.
You should create an empty list. Then, you should do an iteration in each entry
in the ‘list.entries’ and check if the search is a substring of the entries that already
exists.
If the search is a substring, you are going to append this entry in the empty
list that you created previously. Else, you go to the next iteration.
After all, pass as context this new list and render the ‘index.html’ page with
this context.
This is what your project should return when you seach ‘Py’ in the entries.
Specification
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Checklist – Wiki (Project 1)
Clicking on any of the entry names on the search results page should take the
user to that entry’s page.
How To Do This?
Since you are using the index.html file to render the search query, you do not
need to do this step, because you already did in the Index section.
New Page
Specification
Clicking “Create New Page” in the sidebar should take the user to a page
where they can create a new encyclopedia entry.
How To Do This?
You should go to ‘layout.html’ and add <a> tag to the user be able to click in
‘Create New Page’ and go to the create new page.
You should create a new URL and new route to display this page.
Also, you should create a html file to display the components of your page.
After that, in the ‘views.py’ render the page.
Specification
Users should be able to enter a title for the page and, in a textarea, should be
able to enter the Markdown content for the page.
How To Do This?
In the html file, you are going to use the <form> tag to create the textarea for
title and content of the page.
You can set how many rows your textarea will display. Look at this link:
https://www.w3schools.com/tags/tag_textarea.asp
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Checklist – Wiki (Project 1)
Since you are using form with Django, you must use the syntax explained in
Lecture Django in CS50 notes. Look the image below:
Inside the form, you should use two <textarea> tags, one for title and other for
Markdown content. The title will be the title of your tab (green arrow in the image
below) and the Markdown content will be the content displayed in your page (yellow
arrow in the image below).
Specification
Users should be able to click a button to save their new page.
How To Do This?
After creating the <textarea> tags and before closing the <form> tag, use an
<input> tag with ‘type=submit’.
You can change the style of this button using Bootstrap for example. See the
following link:
https://getbootstrap.com/docs/5.0/components/buttons/
At this point, the New Page should be look like:
11
Checklist – Wiki (Project 1)
Specification
When the page is saved, if an encyclopedia entry already exists with the
provided title, the user should be presented with an error message.
Otherwise, the encyclopedia entry should be saved to disk, and the user should
be taken to the new entry’s page.
How To Do This?
Now you are going to work with the ‘views.py’ file. In there, you have to do an
if-else condition to check if you are going to work with the POST method or GET
method. You can use the following notation:
if request.method == ‘POST’:
else:
The POST method basically will handle the data of the form. Inside this if, you
are going to get the information from the form using the following notation, for
example:
title = request.POST[‘title’]
content = request.POST[‘content’]
Then, you have to check if the entry already exists. To do this, you can use the
‘get_entry’ function that we explained in the Util section.
If the ‘get_entry’ does not return None, you should render a html file saying
that this page already exists. Here you are going to do the same way as we explained
in the Entry Page section.
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Checklist – Wiki (Project 1)
If the ‘get_entry’ returns None, you are going to call the conversion to HTML
function and render the entry page.
The GET method basically will handle displaying the ‘New Page’ html file. Thus,
inside of the else you are just going to render the ‘New Page’.
Edit Page
Specification
On each entry page, the user should be able to click a link to be taken to a
page where the user can edit that entry’s Markdown content in a textarea.
How To Do This?
You should create a new URL path and a new route. These two files will be like
the entry page, but in this case the URL should be like ‘edit/<str: title>/’.
To solve this, you can add an <a> tag that redirect the user to this new URL
path.
You can style that using buttons from Bootstrap. See the following link:
https://getbootstrap.com/docs/5.0/components/buttons/
To create a button in your <a> tag you should copy the class from Bootstrap
and put inside de <a> tag. For example:
<a class=”btn btn-primary” href=’…’>
At this point, your entry page should look like this:
13
Checklist – Wiki (Project 1)
Specification
The textarea should be pre-populated with the existing Markdown content of
the page. (i.e., the existing content should be the initial value of the textarea).
How To Do This?
Now you are going to work with the ‘views.py’ file. In there, you have to do an
if-else condition to check if you are going to work with the POST method or GET
method. You can use the following notation:
if request.method == ‘GET’:
else:
The GET method basically will handle displaying the ‘Edit Page’ HTML file.
To pre-populate with the existing Markdown content of the page, you should
use the ‘get_entry’ function.
Then, you need to pass the entry name and the entry content as context from
‘views.py’ to ‘edit’ HTML.
In the ‘edit’ HTML, you are going to use the <form> tag to create the textarea
for title and content of the page.
You can set how many rows your textarea will display. Look at this link:
https://www.w3schools.com/tags/tag_textarea.asp
Since you are using form with Django, you must use the syntax explained in
Lecture Django in CS50 notes. Look the image below:
So far, the page should look like:
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Checklist – Wiki (Project 1)
Note that the title will be the title of your tab (green arrow in the image below)
and the Markdown content will be the content displayed in your page (yellow arrow
in the image below).
Specification
The user should be able to click a button to save the changes made to the
entry.
How To Do This?
Your <input type=”submit”> will be this button to save the changes made to the
entry. You can style this input using Bootstrap:
https://getbootstrap.com/docs/5.0/components/buttons/
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Checklist – Wiki (Project 1)
This information will be sent to the backend (‘views.py’). In the route you
already have the GET method. Now we are going to work with the POST method.
The POST method basically will handle the data of the form. Inside this else,
you are going to get the information from the form using the following notation, for
example:
title = request.POST[‘title’]
content = request.POST[‘content’]
Then, you must save this entry using the ‘save_entry’ function. Check the
‘Understand util.py’ section.
After saving, you should convert this edited entry using the ‘conversion
Markdown to HTML’.
Specification
Once the entry is saved, the user should be redirected back to that entry’s
page.
How To Do This?
This is the last part in the POST method. You are going to render the page with
the edited entry. Remember to pass as context the title and the content of the edited
entry.
Random Page
Specification
Clicking “Random Page” in the sidebar should take user to a random
encyclopedia entry.
How To Do This?
You should create a new url and new route to display this page.
You can use the ‘random library, because there is a function ‘randpm.choice()’
that pick a random entry in the list you pass as input.
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Checklist – Wiki (Project 1)
After that, call the conversion to HTML function and render the page.
Final Step
You should go to ‘layout.html’ and add <a> tag to the user be able to click in
‘Random Page’ and go to the random page.
FAQ
Question
How To Do This?
The reason why the search is not working is because the code didn’t have the
{csrf_token}. Check the Search section to know better.
Question
How To Do This?
When you do the iteration in each entry to if the search input is a substring of
other entries, you have to make all lower case.
To do this, you can use the .lower() Python function to do the comparison. For
example:
if search.lower() in entry.lower():
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Checklist – Wiki (Project 1)
Question
How To Do This?
Check the Edit Page section and you will understand how to do it.
Question
How To Do This?
To solve the formatting of <textarea> tags you should change the properties in
styles.css.
To solve the markdown conversion, look at Convert Markdown to HTML section
and the New Page section.
Question
How To Do This?
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Checklist – Wiki (Project 1)
Check the Edit Page section and you will understand how to do it.
Question
How To Do This?
To solve this, you should go to ‘index.html’ file and you are going to find
basically all done for you. The only thing that you have to add is an <a> tag to solve
this ‘click on any entry name to be taken directly to that entry page’.
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Checklist – Commerce (Project 2)
Summary
Models........................................................................................................................................................3
Create Listing..........................................................................................................................................3
Active Listings Page .............................................................................................................................6
Listing Page .............................................................................................................................................7
Watchlist ................................................................................................................................................. 18
Categories .............................................................................................................................................. 19
Django Admin Interface.................................................................................................................... 20
FAQ........................................................................................................................................................... 20
Important
Throughout this document there will be blue colored links.
These links will help you to solve the project.
Right-click and open in a new tab.
Disclaimer
This is a checklist to help you go through the problem.
The following checklist if for educational purposes only.
Cheating or any other activities are highly discouraged!
2
Checklist – Commerce (Project 2)
Models
Specification
Your application should have at least three class in addition to the User model:
one for auction listings, one for bids, and one for comments made on auction listings.
It’s up to you to decide what fields each model should have, and what the types of
those fields should be. You may have additional class if you would like.
How To Do This?
To solve this problem, we suggest to first understand what models do. Look at
CS50 Web Lecture 4 Notes in the section Django Models:
https://cs50.harvard.edu/web/2020/notes/4/
Basically, you can create Django models to work with databases instead of
directly using SQL queries.
In the Lecture 4, they suggest creating a file called ‘models.py’ where you are
going to outline what data you want to store in your application. Then, Django will
determine the SQL syntax necessary to store information on each of your class.
Thus, before starting the project 2, make sure you really understand the Flight
example gave in CS50 Web Lecture 4 Notes.
After understanding the Flight example, you will be very comfortable working
with models in your project. This models specification will be done while you progress
in your project. Let’s go to the next part!
Create Listing
Specification
Users should be able to visit a page to create a new listing. They should be
able to specify a title for the listing, a text-based description, and what the starting
bid should be. Users should also optionally be able to provide a URL for an image for
the listing and/or a category (e.g. Fashion, Toys, Electronics, Home, etc.).
3
Checklist – Commerce (Project 2)
How To Do This?
Since the new listing information will be stored in the database, you can
create a Model to do this. Look at CS50 Web Lecture 4 Notes to have an idea on how
to do this:
You are going to do something like this in your ‘models.py’, but in your case
you should fulfill the requirements for the listing: title, text-based description,
starting bid, image by URL and/or category. Check the link below to know better how
to create each field for the class:
https://docs.djangoproject.com/en/3.0/ref/forms/fields/#built-in-field-classes
We suggest creating one model for the listing and one model for the category.
Note: remember to create a field for the owner of the listing!
After creating your class, you should create an URL path, a route, and a HTML
file to create a new listing.
In the new HTML file, you should use a <form> tag and have as input the
requirements said above.
Note: since you are using forms with Django, you must use the syntax
explained in Lecture 3 Django in CS50 notes. Look at the image below:
Now you are going to work with the ‘views.py’ file. In there, you have to do an
if-else condition to check if you are going to work with the POST method or GET
method. You can use the following notation:
if request.method == ‘POST’:
else:
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Checklist – Commerce (Project 2)
The POST method basically will handle the data of the form. Inside of this if,
you are going to get the information from the form using the following notation, for
example:
title = request.POST[‘title’]
…
category = request.POST[‘category’]
You can fulfill the model using the notation explained in the Lecture 4 (all in
one line). Look how it is done in CS50 Web Lecture 4 Notes.
Or you can create the Flight class in views.py by creating a variable to store
the model itself. For example:
flight = Flight()
Then you can store each field of the class using the dot operator. For example,
if you want to assign a value to the origin field in the Flight class, you can do the
following:
flight.origin = “New York”
After you’ve set all the fields you call flight.save() and the data will be stored
in the database.
The GET method basically will handle displaying the ‘New Listing Page’ html
file. Thus, inside of the else you are just going to render the HTML file you already
created (the one with the <form> tag).
Active Listings Page
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Checklist – Commerce (Project 2)
Specification
The default route of your web application should let users view all of the
currently active auction listings. For each active listing, this page should display (at
minimum) the title, description, current price, and photo (if one exists for the listing).
How To Do This?
To solve this problem, you should work with the ‘index.html’ file and use the
Bootstrap tools to create a nice ‘Active Listings Page’. You may be interested in use
<div> tag to separate each listing information in boxes, like the image below:
In ‘models.py’ you should create a field in your listing model to set if the listing
is active or not. By now, all your listing should be active. Further in the project, you
will be able to change this status.
In ‘views.py’ you should find a way to display only the active listings. To do this,
you should manipulate your class. Look how it works in CS50 Web Lecture 4 Notes.
In your case, you should filter by the active field.
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Checklist – Commerce (Project 2)
Look at Lecture Django in CS50 notes and check the ‘greet’ function. You
should understand how they pass the context from Django to HTML (image below):
After passing as context this information from ‘views.py’ to the HTML file, you
are going to display the title, description, current price, and photo (if one exists for
the listing). For example, passing the listing as context in the ‘views.py’:
Listings = Listings.objects.filter(active=True)
In ‘index.html’, since you are passing multiple listings, you should do an
iteration to display all listings at a time. For example:
{% for listing in listings %}
…
{% endfor %}
Remember to use the double curly braces to display the information from
‘views.py’ in the HTML file. For example, to display the title of the listing you can use:
{{ listing.title }}
Listing Page
Specification
Clicking on a listing should take users to a page specific to that listing. On that
page, users should be able to view all details about the listing, including the current
price for the listing.
How To Do This?
To do this, in your ‘index.py’, you should use an <a> tag in each listing in your
index. The <a> tag should have as ‘href’ the URL for the listing.
This URL for the listing will be like what you did in Wiki Project. Look at greet
function in CS50 Web Lecture 3 Notes:
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Checklist – Commerce (Project 2)
Note: in this case you should use <int:listing_id> instead of <str:name>.
In this page, you should pass the information from de backend (‘views.py) to
the frontend (HTML file).
In ‘views.py’ you should find a way to display only the active listings. To do this,
you should manipulate your class. Look how it works in CS50 Web Lecture 4 Notes.
In your case, you should filter the category model by the listing field and the
listing model you should get by the id. If you do not remember how to do this, look at
‘Active Listings Page’ section.
Thus, in this page you are going to display the following information:
• Name of the listing: you should display the title of the listing. For example:
{{ listing.title }}
• The image of the listing: it is optional. You are going to display this using the
<img> tag and the image is stored in the same way you have the title. For
example:
{{ listing.image }}
• The description of the listing: you can do the same way as you did for name of
the listing.
• Category of the listing: you can do the same way as you did in name of the
listing, but in this case, you should call the category that you passed as
context. For example:
{{ category.title }}
• The current bid: you are going to display the same way as you display the
name of the listing.
It is up to you decide how many information you want to display from your
Listing class.
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Checklist – Commerce (Project 2)
Note: now you know that you are going to have a starting bid and a current bid
in your listing. Thus, we recommend creating one field for each of these bids.
Specification
If the user is signed in, the user should be able to add the item to their
“Watchlist.” If the item is already on the watchlist, the user should be able to remove
it.
How To Do This?
In this case you should pass a Boolean saying whether the listing of a
particular user is in his watchlist as context in your ‘views.py’.
Look at Lecture Django in CS50 notes and check the ‘greet’ function. You
should understand how they pass the context from Django to HTML (image below):
It might be useful to use the Python in operator.
In the HTML file, you first should check if the user is signed in. To do this, you
can do an if-else condition. For example:
{% if user.is_authenticated %}
…
{% else %}
…
{% endif %}
Inside the if user.is_authenticated, you are going to create a condition based
on this context that you passed. If this condition is True, you are going to display the
logic to remove the listing from the watchlist. If the condition is False, you are going
to display the logic to add the listing to the watchlist. For example, the in_watchlist
is a Boolean variable that stores whether a listing is in the user’s watchlist:
{% if in_watchlist == True %}
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Checklist – Commerce (Project 2)
…
{% else %}
…
{% endif %}
Inside these if-else condition, you can display a button, for example. When the
user clicks on this button, the user can add or remove the listing to his watchlist.
To handle adding the listing in the watchlist, you should create a new URL path
and a new route in ‘views.py’. This URL will be like what you did in ‘Listing Page’. Look
at greet function in CS50 Web Lecture 3 Notes:
Note: in this case you should use <int:listing_id> instead of <str:name>.
In the route, you should get the listing by id. With this id you can get the listing
in the Listing model and add the user in the watchlist field.
You can fulfill the model using the notation explained in the Lecture 4 (all in
one line). Look how it is done in CS50 Web Lecture 4 Notes.
Or you can create the Flight class in views.py by creating a variable to store
the model itself. For example:
flight = Flight()
Then you can store each field of the class using the dot operator. For example,
if you want to assign a value to the origin field in the Flight class, you can do the
following:
flight.origin = “New York”
After you’ve set all the fields you call flight.save() and the data will be stored
in the database.
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Checklist – Commerce (Project 2)
Remember how you did in ‘Create Listing’ section!
To handle the removal of the listing from the watchlist, you should create a
new URL path and a new route in ‘views.py’. This URL will be like what you did in
‘Listing Page’. Look at greet function in CS50 Web Lecture 3 Notes:
Note: in this case you should use <int:listing_id> instead of <str:name>.
In the route, you should get the listing by id. With this id you can get the listing
in the Listing model and remove the user in the watchlist field. You can remove
checking the .remove property in the following link:
https://docs.djangoproject.com/en/3.1/topics/db/queries/
You can fulfill the model using the notation explained in the Lecture 4 (all in
one line). Look how it is done in CS50 Web Lecture 4 Notes.
Or you can create the Flight class in views.py by creating a variable to store
the model itself. For example:
flight = Flight()
Then you can store each field of the class using the dot operator. For example,
if you want to assign a value to the origin field in the Flight class, you can do the
following:
flight.origin = “New York”
After you’ve set all the fields you call flight.save() and the data will be stored
in the database.
Remember how you did in ‘Create Listing’ section and ‘Adding to Watchlist’!
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Checklist – Commerce (Project 2)
Specification
If the user is signed in, the user should be able to bid on the item. The bid must
be at least as large as the starting bid, and must be greater than any other bids that
have been placed (if any). If the bid doesn’t meet those criteria, the user should be
presented with an error.
How To Do This?
You can create a new model in ‘models.py’ for Bids. In this model should have
as fields the offer, the user that gave the bid and the listing (where the offer was
made).
In the listing HTML file, you should first check if the user is authenticated and
if the listing is active. For example, where the listing.active is a Boolean variable that
sets whether the listing is active or not:
{% if user.is_authenticated and listing.active == True %}
…
{% else %}
…
{% endif %}
Inside the if user.is_authenticated and listing.active == Ture, you are going to
use a <form> tag and have as input the bid of the user.
Note: since you are using form with Django, you must use the syntax explained
in Lecture 3 Django in CS50 notes. Look the image below:
To handle submitting the bid, you should create a new URL. This URL will be
like what you did in ‘Listing Page’. Look at greet function in CS50 Web Lecture 3 Notes:
Note: in this case you should use <int:listing_id> instead of <str:name>.
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Checklist – Commerce (Project 2)
Then, you should create a new route for the comment. In this route you should
get the listing by the id. Look how it works in CS50 Web Lecture 4 Notes.
In there, you must do an if condition to check if you are going to work with the
POST method. You can use the following notation:
if request.method == ‘POST’:
The POST method basically will handle the data of the form. Inside this if, you
are going to get the information from the form using the following notation, for
example:
user_bid = request.POST[‘user_bid’]
Then, you must check if the user_bid is greater than the starting bid or the
current bid.
If is not, you should present an error for the user. You can do this by creating
a new HTML file for example.
If the offer is greater than the current bid or the start bid, you should add this
new bid in the model.
You can fulfill the model using the notation explained in the Lecture 4 (all in
one line). Look how it is done in CS50 Web Lecture 4 Notes.
Or you can create the Flight class in views.py by creating a variable to store
the model itself. For example:
flight = Flight()
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Checklist – Commerce (Project 2)
Then you can store each field of the class using the dot operator. For example,
if you want to assign a value to the origin field in the Flight class, you can do the
following:
flight.origin = “New York”
After you’ve set all the fields you call flight.save() and the data will be stored
in the database.
At this point, your project should look like:
Specification
If the user is signed in and is the one who created the listing, the user should
have the ability to “close” the auction from this page, which makes the highest bidder
the winner of the auction and makes the listing no longer active.
How To Do This?
In this case you should pass a Boolean saying whether the particular user is
the owner of the listing as context in your ‘views.py’.
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Checklist – Commerce (Project 2)
You can do this by checking if the user is the field that you created in your
Listing model to handle storing the owner of each listing. Thus, you should pass as
context your Boolean variable.
Look at Lecture Django in CS50 notes and check the ‘greet’ function. You
should understand how they pass the context from Django to HTML (image below):
In the HTML file, you first should check if the user is signed in. To do this, you
can do an if-else condition. For example:
{% if user.is_authenticated %}
…
{% else %}
…
{% endif %}
Inside the if user.is_authenticated, you are going to create a condition based
on this context that you passed. If this condition is True, you are going to display the
logic to close the bid.
Also, you must check if the listing is active or not. For example, the is_owner
is a Boolean variable that stores whether the user is the owner of the listing, and the
listing.active is a Boolean variable that stores whether the listing is active or not:
{% if is_owner == True and listing.active == True%}
…
{% else %}
…
{% endif %}
Inside this if condition, you can display a button, for example. When the user
clicks on this button, the user can close the auction.
To handle closing the listing, you should create a new URL path and a new
route in ‘views.py’. This URL will be like what you did in Listing Page. Look at greet
function in CS50 Web Lecture 3 Notes:
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Checklist – Commerce (Project 2)
Note: in this case you should use <int:listing_id> instead of <str:name>.
In the route, you should get the listing by id. With this id you can get the listing
in the Listing model and set the active field as False.
You can fulfill the model using the notation explained in the Lecture 4 (all in
one line). Look how it is done in CS50 Web Lecture 4 Notes.
Or you can create the Flight class in views.py by creating a variable to store
the model itself. For example:
flight = Flight()
Then you can store each field of the class using the dot operator. For example,
if you want to assign a value to the origin field in the Flight class, you can do the
following:
flight.origin = “New York”
After you’ve set all the fields you call flight.save() and the data will be stored
in the database.
Remember how you did in ‘Create Listing’ section!
Specification
If a user is signed in on a closed listing page, and the user has won that
auction, the page should say so.
How To Do This?
In this case you should pass a Boolean saying whether the particular user has
the current bid in a listing (the one that won the auction) as context in your ‘views.py’.
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Checklist – Commerce (Project 2)
You can do this by checking if the user is the field that you created in your
Listing model to handle storing the user that placed the current bid of each listing.
Thus, you should pass as context your Boolean variable.
Look at Lecture Django in CS50 notes and check the ‘greet’ function. You
should understand how they pass the context from Django to HTML (image below):
In the HTML file, you first should check if the user is the buyer of the listing
and the listing is not active.
For example, the is_winner is a Boolean variable that stores whether the user
is the winner of the listing, and the listing.active is a Boolean variable that stores
whether the listing is active or not:
{% if listing.active == False and is_winner == True %}
…
{% endif %}
Inside the if, you are going to display a message telling the user that he won
the auction.
Specification
Users who are signed in should be able to add comments to the listing page.
The listing page should display all comments that have been made on the listing.
How To Do This?
About the comments, you can create a new model. In this model should have
as fields the comment, the user that gave the comment and the listing (where the
comment was made).
In this section, we must do two things. First receive new comments from the
user and second display the comments.
1. Receive new comments from the user:
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Checklist – Commerce (Project 2)
In the listing HTML file, you are going to first check if the user is authenticated.
For example:
{% if user.is_authenticated %}
…
{% else %}
…
{% endif %}
Inside the if user.is_authenticated, you are going to use a <form> tag and have
as input the comment of the user.
Note: since you are using form with Django, you must use the syntax explained
in Lecture 3 Django in CS50 notes. Look the image below:
To handle submitting the comments, you should create a new URL. This URL
will be similar to what you did in Listing Page. Look at greet function in CS50 Web
Lecture 3 Notes:
Note: in this case you should use <int:listing_id> instead of <str:name>.
Then, you should create a new route for the comment. In this route you should
get the listing by the id. Look how it works in CS50 Web Lecture 4 Notes.
In there, you have to do an if condition to check if you are going to work with
the POST method. You can use the following notation:
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Checklist – Commerce (Project 2)
if request.method == ‘POST’:
The POST method basically will handle the data of the form. Inside this if, you
are going to get the information from the form using the following notation, for
example:
user_comment = request.POST[‘user_comment’]
Then, you should add this information to the Comment model.
You can fulfill the model using the notation explained in the Lecture 4 (all in
one line). Look how it is done in CS50 Web Lecture 4 Notes.
Or you can fulfill the model creating a variable to store the model itself. For
example:
flight = Flight()
Then, instead of doing what is in the image above, you can store each field of
the model by calling the previous variable and using a dot and the name of the field.
For example, if you want to fulfill the origin field in Flight class, you can do the
following:
flight.origin = “New York”
Now, you should do the same idea in your project.
2. Display the comments in the listing:
In the listing page route, you should pass as context the comments for that
listing. Remember to use the following:
comments = Comment.objects.filter(listing=listing)
Look at Lecture Django in CS50 notes and check the ‘greet’ function. You
should understand how they pass the context from Django to HTML (image below):
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Checklist – Commerce (Project 2)
Since you are passing multiple listings, you should do an iteration to display
all the comments at a <div> tag. For example:
{% for comment in comments %}
…
{% endfor %}
Remember to use the double curly braces to display the information from
‘views.py’. For example, to display the comment you can use:
{{ comment.user }}
Watchlist
Specification
Users who are signed in should be able to visit a Watchlist page, which should
display all of the listings that a user has added to their watchlist. Clicking on any of
those listings should take the user to that listing’s page.
How To Do This?
To solve this, first you should pass the user watchlist model to a new HTML
file. You can do this by passing as context. Look at greet function on CS50 Web Lecture
3 Notes:
In this HTML file you are going to display the listings the same way as you did
in the ‘index.html’.
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Categories
Specification
Users should be able to visit a page that displays a list of all listing categories.
Clicking on the name of any category should take the user to a page that displays all
of the active listings in that category.
How To Do This?
To solve this, first you should pass the category model to a new HTML file. You
can do this by passing as context. Look at greet function on CS50 Web Lecture 3
Notes:
Then, you are going to the HTML file and can create a <form> tag to display the
categories options.
Note: since you are using form with Django, you must use the syntax explained
in Lecture 3 Django in CS50 notes. Look the image below:
The form will be handled in a new route, where you are going to display the
specific listings of that category chosen by the user.
Thus, in this new route you should get the values from the form. And then, use
this category to get the listings. Pass this information to the HTML file. Remember
how to do this in the previous sections.
In this HTML file you are going to display the listings the same way as you did
in the ‘index.html’.
Django Admin Interface
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Checklist – Commerce (Project 2)
Specification
Via the Django admin interface, a site administrator should be able to view,
add, edit, and delete any listings, comments, and bids made on the site.
How To Do This?
To solve this, you are going to follow the steps explained in the ‘Django Admin’
at the end of CS50 Web Lecture 4 Notes. Just follow the steps!
FAQ
Specification
When should I use the @login_required decorator in my ‘views.py’?
How To Do This?
You should use this decorator any time you want display the page only if the
user is logged in. For example, you can use this @login_required decorator in the
watchlist page.
Specification
How should I create my Category model?
How To Do This?
Your Category model should have at least two fields. One for the name of the
category, and in this case, you are going to use the CharField.
The other field should have a relationship with the Listing model. In this case,
you should use the ForeignKey field.
Specification
When should I use the ManyToManyField relationship in ‘models.py’?
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Checklist – Commerce (Project 2)
How To Do This?
By default, this table name is generated using the name of the many-to-many
field and the name of the table for the model that contains it.
You should use the ManyToManyField in the watchlist for example. Because
this field will store which users wants to have in the watchlist for each listing.
Thus, you are going to be able to store multiple users in each listing.
For example, Mary and John want to have the Chocolate listing in the
watchlist. Mary wants to have the Cake listing in the watchlist. Daniel wants to have
Ice Cream listing in the watchlist. The ManyToManyField will store this information.
Specification
How To Do This?
The Bids model should store the data about the offer, the user that gave the
offer and a relation between the bid and the listing where the bid was placed.
This relation will be handled by the ForeignKey field.
Specification
How To Do This?
You should create a field in your Listing model to check if the listing is active
or not. You can do this by using the BooleanField.
Then, in your ‘views.py’ you must filter the listing by this Boolean. For example:
listings = Listing.objects.filter(active=True)
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Specification
How To Do This?
Since you are receiving the image by it is URL, you can display the image just
using the <img> tag and in the property ‘src’ you call the listing image. For example:
<img src={{ listing.image }}>
Remember to pass as context to the HTML file the Listing model. If you do not
know how to do this, check the ‘Listing Page’ section.
Look at Lecture Django in CS50 notes and check the ‘greet’ function. You
should understand how they pass the context from Django to HTML (image below):
Specification
How To Do This?
Look on how to do this in the ‘Watchlist’ section. You should pass the watchlist
as context from ‘views.py’ to the HTML file.
Look at Lecture Django in CS50 notes and check the ‘greet’ function. You
should understand how they pass the context from Django to HTML (image below):
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25
TODO - Javascript
styles.css
h1{
text-align: center;
color: gray;
}
.container-style{
margin-bottom: 50px;
margin-left: 50px;
margin-right: 50px;
margin-top: 50px;
}
task.html
<!DOCTYPE html>
<html lang="en">
<head>
<!--Defines what the title of the webpage will be-->
<!--As displayed in the tab of the browser-->
<title>Tasks</title>
<!--Explains to the compiler where the javascript file code is-->
<script src="tasks.js"></script>
<!--Explains to the compiler where the css file is-->
<link href="styles.css" rel="stylesheet">
<!--Explains to the compiler where the Bootstrap documentation is-->
<link
href="https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/css/bootstrap.min.css"
rel="stylesheet">
</head>
2
TODO - Javascript
<body>
<!--Heading of the page-->
<div class="container-style">
<h1>Tasks</h1>
</div>
<div class="container">
<!--Creates an unordered list to display the tasks-->
<!--The javascript code will handle the list items-->
<ul id="tasks" class="list-group"></ul>
</div>
<!--Creates a form to the user inputs a new task-->
<div class="container-style">
<form>
<!--This input field is to type the new task-->
<input id="task" placeholder = "New Task" type="text" class="form-control">
<!--This input field is to create a submit button-->
<input id="submit" type="submit" class="btn btn-light">
</form>
</div>
</body>
</html>
3
TODO - Javascript
tasks.js
document.addEventListener('DOMContentLoaded', () => {
//Select the form tag in HTML to be used later
const form = document.querySelector('form');
//Select the ul tag in HTML to be used later
const ul = document.querySelector('ul');
//Select the submit button in HTML to be used later
const submit = document.querySelector('#submit');
//Select the task input in HTML to be used later
let newtask = document.querySelector('#task');
//Default action for the submit button when you enter on the page
submit.disabled = true;
//Listen for input to be typed into the input field
newtask.addEventListener('keyup', () => {
//When there is nothing typed in the input, turns the submit button disabled
if (newtask.value === '') {
submit.disabled = true;
}
//When there is something typed in the input, turns the submit button enable
else {
submit.disabled = false;
}
});
4
TODO - Javascript
//When submit the task
form.addEventListener('submit', (event) => {
//Prevents the default submission of the form which involves
//either reloading the current page or redirecting to a new one
event.preventDefault();
//We can create HTML elements using the createElement function
//Creates an list item on HTML
const li = document.createElement('li');
//Add newtask value in list item
li.innerHTML = newtask.value;
//We can then add HTML those elements to the DOM using the append function
//Append the list item to unordered list
ul.append(li);
//Clear the value of newtask variable and set it to empty
newtask.value = '';
//Disable button when there is nothing in newtask
submit.disabled = true;
});
});
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Checklist – Mail (Project 3)
Summary
Mail Project ............................................................................................................................... 3
Send Mail ................................................................................................................................... 3
Mailbox ....................................................................................................................................... 4
View Email ................................................................................................................................. 7
Archive and Unarchive ........................................................................................................ 10
Reply........................................................................................................................................... 11
CSS............................................................................................................................................. 14
FAQ............................................................................................................................................. 14
Important
Throughout this document there will be blue colored links.
These links will help you to solve the project.
Right-click and open in a new tab.
Disclaimer
This is a checklist to help you go through the problem.
The following checklist if for educational purposes only.
Cheating or any other activities are highly discouraged!
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Checklist – Mail (Project 3)
Mail Project
The distribution code gives to us all the backend done, so the only files that
you are going to work will be the inbox.js, inbox.html and styles.css.
Remember that the JavaScript will be written in the inbox.js; the HTML will be
written in the inbox.html; and the CSS will be in the styles.css.
Send Mail
Specification
When a user submits the email composition form, add JavaScript code to
actually send the email.
How To Do This?
To solve this bullet point you can create a new function with purpose of
submitting the email.
You should get the values of recipients, subject, and body from the input that
the user gives to the web app. To do this, take a look at this property of JavaScript:
https://www.w3schools.com/jsref/met_document_queryselector.asp
Specification
You’ll likely want to make a POST request to /emails, passing in values for
recipients, subject, and body.
How To Do This?
If you take a look at the API in the Mail Project explanation, you are going to
find a section called “POST/emails”. The CS50’s staff explain how you should send the
information that you are receiving from the frontend to the backend.
You basically are going to get the JavaScript code that they give to you and
make some changes.
We recommend you understand what fetch does before starting this part of
the project.
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Checklist – Mail (Project 3)
Specification
Once the email has been sent, load the user’s sent mailbox.
How To Do This?
To solve this, you should call the function load_mailbox, that is already made
to us in the distribution code and sending as input to the function the mailbox ‘sent’.
We recommend you use the setTimeout in order to wait the fetch call works.
This is interesting to be used because when you use fetch it takes a while to send and
receive the information, so the setTimeout will wait this information go and come to
render the page.
HINT
You are going to notice that if you try to send an email your page is not going
to be redirected to sent mailbox, but to inbox instead. How to solve this?
You should use the preventDefault function because this function will prevent
the default of submit to be refreshing the button.
Mailbox
Specification
When a user visits their Inbox, Sent mailbox, or Archive, load the appropriate
mailbox.
How To Do This?
To solve this problem, you are going to work with the load_mailbox function
that was already initialized for you in the distribution code.
Specification
You’ll likely want to make a GET request to /emails/<mailbox> to request the
emails for a particular mailbox.
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Checklist – Mail (Project 3)
How To Do This?
If you take a look at the API in the Mail Project explanation, you are going to
find a section called “GET/emails/<str:mailbox>”. The CS50’s staff explain how you
should send the information that you are receiving from the frontend to the backend.
You basically are going to get the JavaScript code that they give to you and
make some changes.
We recommend you understand what fetch does before starting this part of
the project.
Specification
When a mailbox is visited, the application should first query the API for the
latest emails in that mailbox.
How To Do This?
This part is already done for you. If you take a look at mailbox route in
views.py, you are going to find on line 95 that the distribution code already returns
the email for the frontend in reverse chronological order.
Specification
When a mailbox is visited, the name of the mailbox should appear at the top
of the page (this part is done for you).
How To Do This?
As the specification already says, this part is done for you.
Specification
Each email should then be rendered in its own box (e.g. as a <div> with a
border) that displays who the email is from, what the subject line is, and the
timestamp of the email.
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Checklist – Mail (Project 3)
How To Do This?
To do this you should create a new function to render in each email its own
box.
PS: When you do the fetch call in the load_mailbox, we recommend you
remember to call this new function inside.
In this function you should do an iteration to work with one email at a time.
We recommend you look at forEach JavaScript property.
After that, you should get the values of recipient, subject and timestamp that
were passed from the backend to the frontend. Store these values in variables.
We recommend using the createElement property to create a new tag in the
HTML file using JavaScript in order to display this information that you grabbed from
the backend.
Use the property innerHTML to display this information in the new tag that you
created.
To complete this task, you have to append the new tag that you created in
JavaScript at an existing tag in the HTML file.
Specification
If the email is unread, it should appear with a white background. If the email
has been read, it should appear with a gray background.
How To Do This?
At this point of the problem, you should create an if-else condition to check if
the email was already read. If this is true, use the style.backgroundColor to set the
email background as gray. Else, use the same property to set the email background
as white.
At this point you project should look like this:
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Checklist – Mail (Project 3)
View Email
Specification
When a user clicks on an email, the user should be taken to a view where they
see the content of that email.
How To Do This?
In the function that you just created to render in each email its own box, you
should use the addEventListener function to be triggered when the user clicks in the
email box.
Specification
You’ll likely want to make a GET request to /emails/<email_id> to request the
email.
How To Do This?
If you take a look at the API in the Mail Project explanation, you are going to
find a section called “GET/emails/100”. The CS50’s staff explain how you should send
the information that you are receiving from the frontend to the backend.
You basically are going to get the JavaScript code that they give to you and
make some changes.
We recommend you understand what fetch does before starting this part of
the project.
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Checklist – Mail (Project 3)
Inside the fetch, you can call another function to display the email with the
specifications that are in the next bullet point.
Specification
Your application should show the email’s sender, recipients, subject,
timestamp, and body.
How To Do This?
This part you should do in your function created to display the email. To solve
this bullet point, you can grab the current email’s properties by the values that you
are grabbing from the fetch call.
For example, to grab the sender you can do email.sender and store this value
in a variable.
To display these values, you should use the property innerHTML in the div tag
that you include in your inbox.html.
Specification
You’ll likely want to add an additional div to inbox.html (in addition to emailsview and compose-view) for displaying the email. Be sure to update your code to hide
and show the right views when navigation options are clicked.
How To Do This?
The first thing you should do is adding a new div tag in inbox.html with an id
property.
To solve this, look at the function compose_email. You are going to find 3 lines,
which the first is the following comment:
// Show compose view and hide other views
The other 2 lines are the ones that you have to understand. When you use
document.querySelector(‘#id’).style.display you are using JavaScript to set if you
want to hide or not the components in that id attribute.
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Checklist – Mail (Project 3)
When you set this to ‘none’, you are hiding the components in the HTML of that
id attribute.
When you set this to ‘block’, you are showing the components in the HTML of
that id attribute.
Specification
See the hint in the Hints section about how to add an event listener to an HTML
element that you’ve added to the DOM.
How To Do This?
In the function that you just created to render in each email its own box, you
should use the addEventListener function to be triggered when the user clicks in the
email box.
Specification
Once the email has been clicked on, you should mark the email as read. Recall
that you can send a PUT request to /emails/<email_id> to update whether an email is
read or not.
How To Do This?
We recommend creating a new function to mark the email as read.
If you take a look at the API in the Mail Project explanation, you are going to
find a section called “PUT/emails/<int:email_id>”. The CS50’s staff explain how you
should send the information that you are receiving from the frontend to the backend.
You basically are going to get the JavaScript code that they give to you and
make some changes.
We recommend you understand what fetch does before starting this part of
the project.
Instead of using ‘archived: true’ in the example that they gave to us, you should
use ‘read: true’.
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Checklist – Mail (Project 3)
You are going to have to call this function in the display email function.
Remember that you only can set if the email was read or not if you are in the inbox
or archive mailbox.
At this point your project should look like this:
Archive and Unarchive
Specification
Allow users to archive and unarchive emails that they have received.
How To Do This?
You should create a new function to solve this issue. Basically, you are going
to use the addEventListener to trigger the fetch call after clicking the submit button.
In the next bullet points we explain better.
Specification
When viewing an Inbox email, the user should be presented with a button that
lets them archive the email. When viewing an Archive email, the user should be
presented with a button that lets them unarchive the email. This requirement does
not apply to emails in the Sent mailbox.
How To Do This?
To solve that you should create a button in your display email function. This
button will represent the archive/unarchive.
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Checklist – Mail (Project 3)
Since this requirement does not apply to emails in the Sent mailbox, you are
going to call the function that handle with showing the archive button. The same way
as you did before for the mark email as read.
Specification
Recall that you can send a PUT request to /emails/<email_id> to mark an email
as archived or unarchived.
How To Do This?
If you take a look at the API in the Mail Project explanation, you are going to
find a section called “PUT/emails/<int:email_id>”. The CS50’s staff explain how you
should send the information that you are receiving from the frontend to the backend.
You basically are going to get the JavaScript code that they give to you and
make some changes.
We recommend you understand what fetch does before starting this part of
the project.
Specification
Once an email has been archived or unarchived, load the user’s inbox.
How To Do This?
After doing the fetch call, remember to call the load_mailbox function to
redirect the user to the inbox.
We recommend you use the window.location.reload() after redirecting the
user to the inbox.
Reply
Specification
Allow users to reply to an email. When viewing an email, the user should be
presented with a “Reply” button that lets them reply to the email.
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Checklist – Mail (Project 3)
How To Do This?
You can do this by adding a <button> tag in the inbox.html.
Specification
When the user clicks the “Reply” button, they should be taken to the email
composition form.
How To Do This?
In the function that you created the display email, you are going to use the
addEventListener to trigger the compose_email function after clicking the submit
button. In the next bullet points we explain better.
Basically, the compose_email function just handle with the situation that you
are creating a new email to someone. Since this case is a reply, you should create a
new function.
After creating this function, you should go to compose_email and create an ifelse condition. This will make your compose_email be used in the reply button and in
the compose mailbox.
Specification
Pre-fill the composition form with the recipient field set to whoever sent the
original email.
How To Do This?
You can pre-fill the composition form by grabbing the current email’s
properties by the values that you are passing as input in this function.
For example, to grab the recipient you can do ‘email.sender’ and store this
value in a variable.
After that, you can use document.querySelector(‘#compose-recipients’).value
and set this value as the same of the variables.
12
Checklist – Mail (Project 3)
Specification
Pre-fill the subject line. If the original email had a subject line of foo, the new
subject line should be Re: foo. (If the subject line already begins with Re: , no need to
add it again.)
How To Do This?
You can pre-fill the composition form by grabbing the current email’s
properties by the values that you are passing as input in this function.
For example, to grab the subject you can do ‘Re: email.subject’ and store this
value in a variable.
After that, you can use document.querySelector(‘#compose-subject’).value
and set this value as the same of the variables.
Specification
Pre-fill the body of the email with a line like "On Jan 1 2020, 12:00 AM
foo@example.com wrote:" followed by the original text of the email.
How To Do This?
You can pre-fill the composition form by grabbing the current email’s
properties by the values that you are passing as input in this function.
For example, to grab the body with the timestamp you can do `On
${email.timestamp} ${email.sender} wrote: ${email.body}.’ and store this value in a
variable.
After that, you can use document.querySelector(‘#compose-body’).value and
set this value as the same of the variables.
At this point your project should look like this:
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Checklist – Mail (Project 3)
CSS
Specification
You have to create your own style for this project.
How To Do This?
We recommend you use CSS and Bootstrap tools.
For example, to create the boxes separating each email, you can use padding
and border properties.
For example, to make the buttons look nice, you can use the Bootstrap buttons.
FAQs
Specification
How To Do This?
If your Javascript changes aren't being reflected in your site, check:
https://stackoverflow.com/questions/8392441/stop-chrome-caching-my-js-files
14
Checklist – Mail (Project 3)
Specification
How To Do This?
This issue happens in the function that handles with submitting the email.
You are going to notice that if you try to send an email your page is not going
to be redirected to Sent mailbox, but to inbox instead. How to solve this?
You should use the preventDefault function because this function will prevent
the default of submit to be refreshing the button.
Specification
How To Do This?
Replace line number 26 in mail/models.py with:
"timestamp": self.timestamp.strftime("%b %d %Y, %I:%M %p"),
This error is caused because strftime function implementation depends on
your operating system.
If you are Mac and Linux user, you will not have this problem.
If you are windows user, you should change the line 26 in models.py to the
following line.
"timestamp": self.timestamp.strftime("%b %#d %Y, %#I:%M %p"),
15
Checklist – Mail (Project 3)
Specification
How To Do This?
When you are testing the ‘send email’ code, remember that you must send an
email to someone that is already registered in your backend.
Do not forget to create two users in the webapp and then send email to each
other.
Specification
How To Do This?
You should listen for an click or submit event on the submit button of the form
(#send) rather than form submission.
Also remember to use the preventDefault() to prevent form submission.
16
CodingBat Warmup 1 - Python
Questions
sleep_in
The parameter weekday is True if it is a weekday, and the parameter vacation
is True if we are on vacation. We sleep in if it is not a weekday or we're on vacation.
Return True if we sleep in.
sleep_in(False, False) → True
sleep_in(True, False) → False
sleep_in(False, True) → True
monkey_trouble
We have two monkeys, a and b, and the parameters a_smile and b_smile
indicate if each is smiling. We are in trouble if they are both smiling or if neither of
them is smiling. Return True if we are in trouble.
monkey_trouble(True, True) → True
monkey_trouble(False, False) → True
monkey_trouble(True, False) → False
sum_double
Given two int values, return their sum. Unless the two values are the same,
then return double their sum.
sum_double(1, 2) → 3
sum_double(3, 2) → 5
sum_double(2, 2) → 8
2
CodingBat Warmup 1 - Python
diff21
Given an int n, return the absolute difference between n and 21, except return
double the absolute difference if n is over 21.
diff21(19) → 2
diff21(10) → 11
diff21(21) → 0
parrot_trouble
We have a loud talking parrot. The "hour" parameter is the current hour time
in the range 0..23. We are in trouble if the parrot is talking and the hour is before 7
or after 20. Return True if we are in trouble.
parrot_trouble(True, 6) → True
parrot_trouble(True, 7) → False
parrot_trouble(False, 6) → False
makes10
Given 2 ints, a and b, return True if one if them is 10 or if their sum is 10.
makes10(9, 10) → True
makes10(9, 9) → False
makes10(1, 9) → True
near_hundred
Given an int n, return True if it is within 10 of 100 or 200. Note: abs(num)
computes the absolute value of a number.
3
CodingBat Warmup 1 - Python
near_hundred(93) → True
near_hundred(90) → True
near_hundred(89) → False
pos_neg
Given 2 int values, return True if one is negative and one is positive. Except if
the parameter "negative" is True, then return True only if both are negative.
pos_neg(1, -1, False) → True
pos_neg(-1, 1, False) → True
pos_neg(-4, -5, True) → True
not_string
Given a string, return a new string where "not " has been added to the front.
However, if the string already begins with "not", return the string unchanged.
not_string('candy') → 'not candy'
not_string('x') → 'not x'
not_string('not bad') → 'not bad'
missing_char
Given a non-empty string and an int n, return a new string where the char at
index n has been removed. The value of n will be a valid index of a char in the original
string (i.e. n will be in the range 0..len(str)-1 inclusive).
missing_char('kitten', 1) → 'ktten'
missing_char('kitten', 0) → 'itten'
missing_char('kitten', 4) → 'kittn'
4
CodingBat Warmup 1 - Python
front_back
Given a string, return a new string where the first and last chars have been
exchanged.
front_back('code') → 'eodc'
front_back('a') → 'a'
front_back('ab') → 'ba'
front3
Given a string, we'll say that the front is the first 3 chars of the string. If the
string length is less than 3, the front is whatever is there. Return a new string which
is 3 copies of the front.
front3('Java') → 'JavJavJav'
front3('Chocolate') → 'ChoChoCho'
front3('abc') → 'abcabcabc'
5
CodingBat Warmup 1 - Python
Solutions
sleep_in
def sleep_in(weekday,vacation):
if not weekday or vacation:
return True
else:
return False
monkey_trouble
def monkey_trouble(a_smile,b_smile):
if a_smile and b_smile:
return True
if not a_smile and not b_smile:
return False
sum_double
def sum_double(a,b):
if a == b:
return 2 * (a + b)
else:
return a + b
diff21
def diff21(n):
6
CodingBat Warmup 1 - Python
if n > 21:
return 2 * abs(n - 21)
else:
return abs(n - 21)
parrot_trouble
def parrot_trouble(talking,hour):
if talking and (hour < 7 or hour > 20):
return True
else:
return False
makes10
def makes10(a,b):
if (a + b == 10) or a == 10 or b == 10:
return True
else:
return False
near_hundred
def near_hundred(n):
if abs(n - 100) <= 10 or abs(n - 200) <= 10:
return True
else:
return False
7
CodingBat Warmup 1 - Python
pos_neg
def pos_neg(a,b,negative):
if (a < 0 and b < 0) and negative is True:
return True
elif negative is True:
return False
elif (a > 0 and b < 0) or (a < 0 and b > 0):
return True
else:
return False
not_string
def not_string(str):
if len(str) >= 3 and str[:3] == “not”:
return str
return “not” + str
missing_char
def missing_char(str,n):
front = str[:n]
back = str[n+1:]
return front + back
8
CodingBat Warmup 1 - Python
front_back
def front_back(str):
if len(str) <= 1:
return str
mid = str[1: len(str)-1]
return str[len(str)-1] + mid + str[0]
front3
def front3(str):
front_end = 3
if len(str) < front_end:
front_end = len(str)
front = str[:front_end]
return front + front + front
9
CodingBat Warmup 2 - Python
Questions
string_times
Given a string and a non-negative int n, return a larger string that is n copies
of the original string.
string_times('Hi', 2) → 'HiHi'
string_times('Hi', 3) → 'HiHiHi'
string_times('Hi', 1) → 'Hi'
front_times
Given a string and a non-negative int n, we'll say that the front of the string is
the first 3 chars, or whatever is there if the string is less than length 3. Return n
copies of the front;
front_times('Chocolate', 2) → 'ChoCho'
front_times('Chocolate', 3) → 'ChoChoCho'
front_times('Abc', 3) → 'AbcAbcAbc'
string_bits
Given a string, return a new string made of every other char starting with the
first, so "Hello" yields "Hlo".
string_bits('Hello') → 'Hlo'
string_bits('Hi') → 'H'
string_bits('Heeololeo') → 'Hello'
2
CodingBat Warmup 2 - Python
string_splosion
Given a non-empty string like "Code" return a string like "CCoCodCode".
string_splosion('Code') → 'CCoCodCode'
string_splosion('abc') → 'aababc'
string_splosion('ab') → 'aab'
last2
Given a string, return the count of the number of times that a substring length
2 appears in the string and also as the last 2 chars of the string, so "hixxxhi" yields 1
(we won't count the end substring).
last2('hixxhi') → 1
last2('xaxxaxaxx') → 1
last2('axxxaaxx') → 2
array_count9
Given an array of ints, return the number of 9's in the array.
array_count9([1, 2, 9]) → 1
array_count9([1, 9, 9]) → 2
array_count9([1, 9, 9, 3, 9]) → 3
3
CodingBat Warmup 2 - Python
array_front9
Given an array of ints, return True if one of the first 4 elements in the array is
a 9. The array length may be less than 4.
array_front9([1, 2, 9, 3, 4]) → True
array_front9([1, 2, 3, 4, 9]) → False
array_front9([1, 2, 3, 4, 5]) → False
array123
Given an array of ints, return True if the sequence of numbers 1, 2, 3 appears
in the array somewhere.
array123([1, 1, 2, 3, 1]) → True
array123([1, 1, 2, 4, 1]) → False
array123([1, 1, 2, 1, 2, 3]) → True
string_match
Given 2 strings, a and b, return the number of the positions where they contain
the same length 2 substring. So "xxcaazz" and "xxbaaz" yields 3, since the "xx", "aa",
and "az" substrings appear in the same place in both strings.
string_match('xxcaazz', 'xxbaaz') → 3
string_match('abc', 'abc') → 2
string_match('abc', 'axc') → 0
4
CodingBat Warmup 2 - Python
Solutions
string_times
def string_times(str,n):
return n * str
front_times
def front_times(str,n):
if len(str) < 3:
return n * str
else:
return n * str[0:3]
string_bits
def string_bits(str):
word = “”
for i in range(len(str)):
if i % 2 == 0:
word += str[i:i+1]
return word
string_splosion
def string_splosion(str):
word = “”
for i in range(1, len(str)+1):
word += str[0:i]
return word
5
CodingBat Warmup 2 - Python
last2
def last2(str):
word = “”
count = 0
for i in range(len(str)-2):
if str[i:i+2] == word
count += 1
return count
array_count9
def array_count9(nums):
count = 0
for i in nums:
if i == 9:
return count
array_front9
def array_front9(nums):
end = len(nums)
if end > 4:
end = 4
for i in range(end):
if nums[i] == 9:
return True
return False
6
CodingBat Warmup 2 - Python
array123
def array123(nums):
for i in range(len(nums)-2):
if nums[i] == 1 and nums[i+1] == 2 and nums[i+2] == 3:
return True
return False
string_match
def string_match(a,b):
count = 0
for i in range(len(a)-1):
if a[i:i+2] == b[i:i+2]:
count += 1
return count
7
CodingBat String 1 - Python
Questions
hello_name
Given a string name, e.g. "Bob", return a greeting of the form "Hello Bob!".
hello_name('Bob') → 'Hello Bob!'
hello_name('Alice') → 'Hello Alice!'
hello_name('X') → 'Hello X!'
make_abba
Given two strings, a and b, return the result of putting them together in the
order abba, e.g. "Hi" and "Bye" returns "HiByeByeHi".
make_abba('Hi', 'Bye') → 'HiByeByeHi'
make_abba('Yo', 'Alice') → 'YoAliceAliceYo'
make_abba('What', 'Up') → 'WhatUpUpWhat'
make_tags
The web is built with HTML strings like "<i>Yay</i>" which draws Yay as italic
text. In this example, the "i" tag makes <i> and </i> which surround the word "Yay".
Given tag and word strings, create the HTML string with tags around the word, e.g.
"<i>Yay</i>".
make_tags('i', 'Yay') → '<i>Yay</i>'
make_tags('i', 'Hello') → '<i>Hello</i>'
make_tags('cite', 'Yay') → '<cite>Yay</cite>'
2
CodingBat String 1 - Python
make_out_word
Given an "out" string length 4, such as "<<>>", and a word, return a new string
where the word is in the middle of the out string, e.g. "<<word>>".
make_out_word('<<>>', 'Yay') → '<<Yay>>'
make_out_word('<<>>', 'WooHoo') → '<<WooHoo>>'
make_out_word('[[]]', 'word') → '[[word]]'
extra_end
Given a string, return a new string made of 3 copies of the last 2 chars of the
original string. The string length will be at least 2.
extra_end('Hello') → 'lololo'
extra_end('ab') → 'ababab'
extra_end('Hi') → 'HiHiHi'
first_two
Given a string, return the string made of its first two chars, so the String
"Hello" yields "He". If the string is shorter than length 2, return whatever there is, so
"X" yields "X", and the empty string "" yields the empty string "".
first_two('Hello') → 'He'
first_two('abcdefg') → 'ab'
first_two('ab') → 'ab'
3
CodingBat String 1 - Python
first_half
Given a string of even length, return the first half. So the string "WooHoo"
yields "Woo".
first_half('WooHoo') → 'Woo'
first_half('HelloThere') → 'Hello'
first_half('abcdef') → 'abc'
without_end
Given a string, return a version without the first and last char, so "Hello" yields
"ell". The string length will be at least 2.
without_end('Hello') → 'ell'
without_end('java') → 'av'
without_end('coding') → 'odin'
combo_string
Given 2 strings, a and b, return a string of the form short+long+short, with the
shorter string on the outside and the longer string on the inside. The strings will not
be the same length, but they may be empty (length 0).
combo_string('Hello', 'hi') → 'hiHellohi'
combo_string('hi', 'Hello') → 'hiHellohi'
combo_string('aaa', 'b') → 'baaab'
4
CodingBat String 1 - Python
non_start
Given 2 strings, return their concatenation, except omit the first char of each.
The strings will be at least length 1.
non_start('Hello', 'There') → 'ellohere'
non_start('java', 'code') → 'avaode'
non_start('shotl', 'java') → 'hotlava'
left2
Given a string, return a "rotated left 2" version where the first 2 chars are
moved to the end. The string length will be at least 2.
left2('Hello') → 'lloHe'
left2('java') → 'vaja'
left2('Hi') → 'Hi'
5
CodingBat String 1 - Python
Solutions
hello_name
def hello_name(name):
word = “Hello”
word = word + name + “!”
return word
make_abba
def make_abba(a,b):
return a + b + b + a
make_tags
def make_tags(tag,word):
word1 = “<” + tag + “>”
word2 = word
word3 = “</” + tag + “/>”
finalW = word1 + word2 + word3
return finalW
make_out_word
def make_out_word(out,word):
size = len(out)//2
pal = out[0:size] + word + out[size:]
return pal
6
CodingBat String 1 - Python
extra_end
def extra_end(str):
syl = len(str) - 2
word =3 * str[syl:]
return word
first_two
def first_two(str):
if len(str) < 2:
return str
else:
return str[0:2]
first_half
def first_half(str):
size = len(str) / 2
word = “”
word = str[0:size]
return word
without_end
def without_end(str):
word = str[1:len(str)-1]
return word
7
CodingBat String 1 - Python
combo_string
def combo_string(str):
if len(a) > len(b):
long = a
short = b
else:
long = b
short = a
word = short + long + short
return word
non_start
def non_start(a,b):
word1 = a[1: ]
word1 = b[1: ]
fWord = word1 + word2
return fWord
left2
def left2(str):
syl = str[0:2]
word = str[2: ] + syl
return fWord
8
CodingBat String 2 - Python
Questions
double_char
Given a string, return a string where for every char in the original, there are
two chars.
double_char('The') → 'TThhee'
double_char('AAbb') → 'AAAAbbbb'
double_char('Hi-There') → 'HHii--TThheerree'
count_hi
Return the number of times that the string "hi" appears anywhere in the given
string.
count_hi('abc hi ho') → 1
count_hi('ABChi hi') → 2
count_hi('hihi') → 2
cat_dog
Return True if the string "cat" and "dog" appear the same number of times in
the given string.
cat_dog('catdog') → True
cat_dog('catcat') → False
cat_dog('1cat1cadodog') → True
count_code
2
CodingBat String 2 - Python
Return the number of times that the string "code" appears anywhere in the
given string, except we'll accept any letter for the 'd', so "cope" and "cooe" count.
count_code('aaacodebbb') → 1
count_code('codexxcode') → 2
count_code('cozexxcope') → 2
end_other
Given two strings, return True if either of the strings appears at the very end
of the other string, ignoring upper/lower case differences (in other words, the
computation should not be "case sensitive"). Note: s.lower() returns the lowercase
version of a string.
end_other('Hiabc', 'abc') → True
end_other('AbC', 'HiaBc') → True
end_other('abc', 'abXabc') → True
xyz_there
Return True if the given string contains an appearance of "xyz" where the xyz
is not directly preceeded by a period (.). So "xxyz" counts but "x.xyz" does not.
xyz_there('abcxyz') → True
xyz_there('abc.xyz') → False
xyz_there('xyz.abc') → True
Solutions
3
CodingBat String 2 - Python
double_char
def double_char(str):
word = ""
for i in str:
word += i + i
return word
count_hi
def count_hi(str):
count = 0
for i in range(len(str)-1):
if str[i:i+2] == "hi":
count+=1
return count
cat_dog
def cat_dog(str):
countCat = 0
countDog = 0
for i in range(len(str)-2):
if(str[i:i+3] =="cat"):
countCat+=1
if(str[i:i+3] =="dog"):
countDog+=1
return (countCat == countDog)
count_code
4
CodingBat String 2 - Python
def count_code(str):
count = 0
if(len(str)<4):
return 0
else:
for i in range(len(str)-3):
if(str[i:i+1] == "c" and str[i+1:i+2] == "o" and str[i+3:i+4] == "e"):
count+=1
return count
end_other
def end_other(a, b):
word1 = a.lower()
word2 = b.lower()
if(len(word1)<len(word2)):
small = word1
big = word2
else:
small = word2
big = word1
if(big[len(big)-len(small):] == small):
return True
else:
return False
xyz_there
5
CodingBat String 2 - Python
def xyz_there(str):
word = "xyz"
for i in range(len(str)-2):
if (str[i:i+3] == word and str[i-1:i] != "."):
return True
return False
6
CodingBat List 1 - Python
Questions
first_last6
Given an array of ints, return True if 6 appears as either the first or last
element in the array. The array will be length 1 or more.
first_last6([1, 2, 6]) → True
first_last6([6, 1, 2, 3]) → True
first_last6([13, 6, 1, 2, 3]) → False
same_first_last
Given an array of ints, return True if the array is length 1 or more, and the first
element and the last element are equal.
same_first_last([1, 2, 3]) → False
same_first_last([1, 2, 3, 1]) → True
same_first_last([1, 2, 1]) → True
make_pi
Return an int array length 3 containing the first 3 digits of pi, {3, 1, 4}.
make_pi() → [3, 1, 4]
common_end
Given 2 arrays of ints, a and b, return True if they have the same first element
or they have the same last element. Both arrays will be length 1 or more.
common_end([1, 2, 3], [7, 3]) → True
common_end([1, 2, 3], [7, 3, 2]) → False
common_end([1, 2, 3], [1, 3]) → True
2
CodingBat List 1 - Python
sum3
Given an array of ints length 3, return the sum of all the elements.
sum3([1, 2, 3]) → 6
sum3([5, 11, 2]) → 18
sum3([7, 0, 0]) → 7
rotate_left3
Given an array of ints length 3, return an array with the elements "rotated
left" so {1, 2, 3} yields {2, 3, 1}.
rotate_left3([1, 2, 3]) → [2, 3, 1]
rotate_left3([5, 11, 9]) → [11, 9, 5]
rotate_left3([7, 0, 0]) → [0, 0, 7]
reverse3
Given an array of ints length 3, return a new array with the elements in
reverse order, so {1, 2, 3} becomes {3, 2, 1}.
reverse3([1, 2, 3]) → [3, 2, 1]
reverse3([5, 11, 9]) → [9, 11, 5]
reverse3([7, 0, 0]) → [0, 0, 7]
3
CodingBat List 1 - Python
max_end3
Given an array of ints length 3, figure out which is larger, the first or last
element in the array, and set all the other elements to be that value. Return the
changed array.
max_end3([1, 2, 3]) → [3, 3, 3]
max_end3([11, 5, 9]) → [11, 11, 11]
max_end3([2, 11, 3]) → [3, 3, 3]
sum2
Given an array of ints, return the sum of the first 2 elements in the array. If
the array length is less than 2, just sum up the elements that exist, returning 0 if the
array is length 0.
sum2([1, 2, 3]) → 3
sum2([1, 1]) → 2
sum2([1, 1, 1, 1]) → 2
middle_way
Given 2 int arrays, a and b, each length 3, return a new array length 2
containing their middle elements.
middle_way([1, 2, 3], [4, 5, 6]) → [2, 5]
middle_way([7, 7, 7], [3, 8, 0]) → [7, 8]
middle_way([5, 2, 9], [1, 4, 5]) → [2, 4]
4
CodingBat List 1 - Python
make_ends
Given an array of ints, return a new array length 2 containing the first and last
elements from the original array. The original array will be length 1 or more.
make_ends([1, 2, 3]) → [1, 3]
make_ends([1, 2, 3, 4]) → [1, 4]
make_ends([7, 4, 6, 2]) → [7, 2]
has23
Given an int array length 2, return True if it contains a 2 or a 3.
has23([2, 5]) → True
has23([4, 3]) → True
has23([4, 5]) → False
5
CodingBat List 1 - Python
Solutions
first_last6
def first_last6(nums):
if nums[0] == 6 or nums[len(nums)-1] == 6:
return True
else:
return False
same_first_last
def same_first_last(nums):
if len(nums) >= 1 and nums[0] == nums[-1]:
return True
else:
return False
make_pi
def make_pi():
return [3,1,4]
common_end
def common_end(a,b):
if a[0] == b[0] or a[len(a) - 1] == b[len(b) - 1]:
return True
else:
return False
6
CodingBat List 1 - Python
sum3
def sum3(nums):
return nums[0] + nums[1] + nums[2]
rotate_left3
def rotate_left3(nums):
return [nums[1], nums[len(nums)-1], nums[0]]
reverse3
def reverse3(nums):
return [nums[len(nums)-1], nums[1], nums[0]]
max_end3
def max_end3(nums):
if nums[0] > nums[-1]:
return [nums[0], nums[0], nums[0]]
else:
return [nums[-1], nums[-1], nums[-1]]
sum2
def sum2(nums):
if len(nums) == 0:
return 0
elif len(nums) < 2:
return nums[0]
else:
return nums[0] + nums[1]
7
CodingBat List 1 - Python
middle_way
def middle_way(a,b):
return [a[1], b[1]]
make_ends
def make_ends(nums):
return [nums[0], nums[len(nums)-1]]
has23
def has23(a,b):
if (nums[0] == 2 or nums[1] == 2) or (nums[0] == 3 or nums[1] == 3):
return True
else:
return False
8
CodingBat Lists 2 - Python
Questions
count_evens
Return the number of even ints in the given array. Note: the % "mod" operator
computes the remainder, e.g. 5 % 2 is 1.
count_evens([2, 1, 2, 3, 4]) → 3
count_evens([2, 2, 0]) → 3
count_evens([1, 3, 5]) → 0
big_diff
Given an array length 1 or more of ints, return the difference between the
largest and smallest values in the array. Note: the built-in min(v1, v2) and max(v1, v2)
functions return the smaller or larger of two values.
big_diff([10, 3, 5, 6]) → 7
big_diff([7, 2, 10, 9]) → 8
big_diff([2, 10, 7, 2]) → 8
centered_average
Return the "centered" average of an array of ints, which we'll say is the mean
average of the values, except ignoring the largest and smallest values in the array.
If there are multiple copies of the smallest value, ignore just one copy, and likewise
for the largest value. Use int division to produce the final average. You may assume
that the array is length 3 or more.
centered_average([1, 2, 3, 4, 100]) → 3
centered_average([1, 1, 5, 5, 10, 8, 7]) → 5
centered_average([-10, -4, -2, -4, -2, 0]) → -3
sum13
2
CodingBat Lists 2 - Python
Return the sum of the numbers in the array, returning 0 for an empty array.
Except the number 13 is very unlucky, so it does not count and numbers that come
immediately after a 13 also do not count.
sum13([1, 2, 2, 1]) → 6
sum13([1, 1]) → 2
sum13([1, 2, 2, 1, 13]) → 6
sum67
Return the sum of the numbers in the array, except ignore sections of
numbers starting with a 6 and extending to the next 7 (every 6 will be followed by at
least one 7). Return 0 for no numbers.
sum67([1, 2, 2]) → 5
sum67([1, 2, 2, 6, 99, 99, 7]) → 5
sum67([1, 1, 6, 7, 2]) → 4
has22
Given an array of ints, return True if the array contains a 2 next to a 2
somewhere.
has22([1, 2, 2]) → True
has22([1, 2, 1, 2]) → False
has22([2, 1, 2]) → False
3
CodingBat Lists 2 - Python
Solutions
count_evens
def count_evens(nums):
count = 0
for i in range(len(nums)):
if nums[i] % 2 == 0:
count += 1
return count
bid_diff
def big_diff(nums):
return max(nums) - min(nums)
centered_average
def centered_average(nums):
nums.sort()
count = 0
total = 0
for i in range(1, len(nums) - 1):
count += 1
total += nums[i]
return total / count
4
CodingBat Lists 2 - Python
sum13
def sum13(nums):
total = 0
skip = False
if len(nums) == 0:
return 0
else:
for i in range(len(nums)):
if nums[i] == 13:
skip = True
elif skip:
skip = False
else:
total += nums[i]
return total
sum67
def sum67(nums):
total = 0
skip = False
for i in range(len(nums)):
if nums[i] == 6:
skip = True
elif nums[i] == 7 and skip:
skip = False
5
CodingBat Lists 2 - Python
elif not skip:
total += nums[i]
return total
has22
def has22(nums):
has2 = False
for i in range(len(nums)):
if has2 and nums[i] == 2:
return True
elif nums[i] == 2:
has2 = True
else:
has2 = False
return False
6
CodingBat Logic 1 - Python
Questions
cigar_party
When squirrels get together for a party, they like to have cigars. A squirrel
party is successful when the number of cigars is between 40 and 60, inclusive. Unless
it is the weekend, in which case there is no upper bound on the number of cigars.
Return True if the party with the given values is successful, or False otherwise.
cigar_party(30, False) → False
cigar_party(50, False) → True
cigar_party(70, True) → True
date_fashion
You and your date are trying to get a table at a restaurant. The parameter
"you" is the stylishness of your clothes, in the range 0..10, and "date" is the stylishness
of your date's clothes. The result getting the table is encoded as an int value with
0=no, 1=maybe, 2=yes. If either of you is very stylish, 8 or more, then the result is 2
(yes). With the exception that if either of you has style of 2 or less, then the result is
0 (no). Otherwise, the result is 1 (maybe).
date_fashion(5, 10) → 2
date_fashion(5, 2) → 0
date_fashion(5, 5) → 1
squirrel_play
2
CodingBat Logic 1 - Python
The squirrels in Palo Alto spend most of the day playing. In particular, they
play if the temperature is between 60 and 90 (inclusive). Unless it is summer, then
the upper limit is 100 instead of 90. Given an int temperature and a boolean
is_summer, return True if the squirrels play and False otherwise.
squirrel_play(70, False) → True
squirrel_play(95, False) → False
squirrel_play(95, True) → True
caught_speeding
You are driving a little too fast, and a police officer stops you. Write code to
compute the result, encoded as an int value: 0=no ticket, 1=small ticket, 2=big ticket.
If speed is 60 or less, the result is 0. If speed is between 61 and 80 inclusive, the result
is 1. If speed is 81 or more, the result is 2. Unless it is your birthday -- on that day,
your speed can be 5 higher in all cases.
caught_speeding(60, False) → 0
caught_speeding(65, False) → 1
caught_speeding(65, True) → 0
sorta_sum
Given 2 ints, a and b, return their sum. However, sums in the range 10..19
inclusive, are forbidden, so in that case just return 20.
sorta_sum(3, 4) → 7
sorta_sum(9, 4) → 20
sorta_sum(10, 11) → 21
alarm_clock
3
CodingBat Logic 1 - Python
Given a day of the week encoded as 0=Sun, 1=Mon, 2=Tue, ...6=Sat, and a boolean
indicating if we are on vacation, return a string of the form "7:00" indicating when the
alarm clock should ring. Weekdays, the alarm should be "7:00" and on the weekend
it should be "10:00". Unless we are on vacation -- then on weekdays it should be
"10:00" and weekends it should be "off".
alarm_clock(1, False) → '7:00'
alarm_clock(5, False) → '7:00'
alarm_clock(0, False) → '10:00'
love6
The number 6 is a truly great number. Given two int values, a and b, return
True if either one is 6. Or if their sum or difference is 6. Note: the function abs(num)
computes the absolute value of a number.
love6(6, 4) → True
love6(4, 5) → False
love6(1, 5) → True
in1to10
Given a number n, return True if n is in the range 1..10, inclusive. Unless
outside_mode is True, in which case return True if the number is less or equal to 1, or
greater or equal to 10.
in1to10(5, False) → True
in1to10(11, False) → False
in1to10(11, True) → True
near_ten
4
CodingBat Logic 1 - Python
Given a non-negative number "num", return True if num is within 2 of a
multiple of 10.
Note: (a % b) is the remainder of dividing a by b, so (7 % 5) is 2.
near_ten(12) → True
near_ten(17) → False
near_ten(19) → True
Solutions
5
CodingBat Logic 1 - Python
cigar_party
def cigar_party(cigars, is_weekend):
if is_weekend == True:
return cigars >= 40
else:
return cigars >= 40 and cigars <= 60
date_fashion
def date_fashion(you, date):
if you <= 2 or date <= 2:
return 0
elif you >= 8 or date >= 8:
return 2
else:
return 1
squirrel_play
def squirrel_play(temp, is_summer):
if temp >= 60:
if is_summer:
if temp <= 100:
return True
else:
return False
else:
6
CodingBat Logic 1 - Python
if temp <= 90:
return True
else:
return False
else:
return False
caught_speeding
def caught_speeding(speed, is_birthday):
if is_birthday:
speed -= 5
if speed <= 60:
return 0
return 1 if 61 <= speed <= 80 else 2
sorta_sum
def sorta_sum(a, b):
sum = a + b
if 10 <= sum <= 19:
return 20
else:
return sum
alarm_clock
7
CodingBat Logic 1 - Python
def alarm_clock(day, vacation):
week_day = day not in (0, 6)
if vacation:
if week_day:
return '10:00'
else:
return 'off'
else:
if week_day:
return '7:00'
else:
return '10:00'
love6
def love6(a, b):
if (a == 6 or b == 6 or (a+b) == 6 or abs(a-b) == 6):
return True
else:
return False
in1to10
def in1to10(n, outside_mode):
if outside_mode:
return n <= 1 or n >= 10
return 1 <= n <= 10
near_ten
8
CodingBat Logic 1 - Python
def near_ten(num):
num_mod_10 = num % 10
return num_mod_10 <= 2 or num_mod_10 >= 8
9
CodingBat Logic 2 - Python
Questions
make_bricks
We want to make a row of bricks that is goal inches long. We have a number
of small bricks (1 inch each) and big bricks (5 inches each). Return True if it is possible
to make the goal by choosing from the given bricks. This is a little harder than it looks
and can be done without any loops.
make_bricks(3, 1, 8) → True
make_bricks(3, 1, 9) → False
make_bricks(3, 2, 10) → True
lone_sum
Given 3 int values, a b c, return their sum. However, if one of the values is the
same as another of the values, it does not count towards the sum.
lone_sum(1, 2, 3) → 6
lone_sum(3, 2, 3) → 2
lone_sum(3, 3, 3) → 0
lucky_sum
Given 3 int values, a b c, return their sum. However, if one of the values is 13
then it does not count towards the sum and values to its right do not count. So for
example, if b is 13, then both b and c do not count.
lucky_sum(1, 2, 3) → 6
lucky_sum(1, 2, 13) → 3
lucky_sum(1, 13, 3) → 1
2
CodingBat Logic 2 - Python
no_teen_sum
Given 3 int values, a b c, return their sum. However, if any of the values is a
teen -- in the range 13..19 inclusive -- then that value counts as 0, except 15 and 16
do not count as a teens. Write a separate helper "def fix_teen(n):"that takes in an int
value and returns that value fixed for the teen rule. In this way, you avoid repeating
the teen code 3 times (i.e. "decomposition"). Define the helper below and at the same
indent level as the main no_teen_sum().
no_teen_sum(1, 2, 3) → 6
no_teen_sum(2, 13, 1) → 3
no_teen_sum(2, 1, 14) → 3
round_sum
For this problem, we'll round an int value up to the next multiple of 10 if its
rightmost digit is 5 or more, so 15 rounds up to 20. Alternately, round down to the
previous multiple of 10 if its rightmost digit is less than 5, so 12 rounds down to 10.
Given 3 ints, a b c, return the sum of their rounded values. To avoid code repetition,
write a separate helper "def round10(num):" and call it 3 times. Write the helper
entirely below and at the same indent level as round_sum().
round_sum(16, 17, 18) → 60
round_sum(12, 13, 14) → 30
round_sum(6, 4, 4) → 10
3
CodingBat Logic 2 - Python
close_far
Given three ints, a b c, return True if one of b or c is "close" (differing from a
by at most 1), while the other is "far", differing from both other values by 2 or more.
Note: abs(num) computes the absolute value of a number.
close_far(1, 2, 10) → True
close_far(1, 2, 3) → False
close_far(4, 1, 3) → True
make_chocolate
We want make a package of goal kilos of chocolate. We have small bars (1 kilo
each) and big bars (5 kilos each). Return the number of small bars to use, assuming
we always use big bars before small bars. Return -1 if it can't be done.
make_chocolate(4, 1, 9) → 4
make_chocolate(4, 1, 10) → -1
make_chocolate(4, 1, 7) → 2
4
CodingBat Logic 2 - Python
Solutions
make_bricks
def make_bricks(small, big, goal):
big_needed = min(big, goal // 5)
return goal - (big_needed * 5) <= small
lone_sum
def lone_sum(a, b, c):
sum = 0
if a not in [b,c]:
sum += a
if b not in [a,c]:
sum += b
if c not in [a,b]:
sum += c
return sum
lucky_sum
def lucky_sum(a, b, c):
sum = 0
for n in (a, b, c):
if n != 13:
sum += n
else:
break
return sum
5
CodingBat Logic 2 - Python
no_teen_sum
def no_teen_sum(a, b, c):
nums = (a, b, c)
sum = 0
for i in range(len(nums)):
sum += fix_teen(nums[i])
return sum
def fix_teen(n):
if n != 15 and n!= 16 and 13 <= n <= 19:
return 0
else:
return n
round_sum
def round_sum(a, b, c):
return round10(a)+round10(b)+round10(c)
def round10(num):
return (num+5)/10*10
6
CodingBat Logic 2 - Python
close_far
def close_far(a, b, c):
ab_diff = abs(a - b)
ac_diff = abs(a - c)
bc_diff = abs(b - c)
if (ab_diff <= 1 and ac_diff >= 2 and bc_diff >= 2) != (ac_diff <= 1 and ab_diff >= 2 and
bc_diff >= 2):
return True
else:
return False
make_chocolate
def make_chocolate(small, big, goal):
if goal >= 5 * big:
remainder = goal - 5 * big
else:
remainder = goal % 5
if remainder <= small:
return remainder
return -1
7
SQL Boat
Questions
Lesson 1: SELECT queries 101
1.
2.
3.
4.
5.
Find the title of each film
Find the director of each film
Find the title and director of each film
Find the title and year of each film
Find all the information about each film
Lesson 2: Queries with constraints (Pt. 1)
1.
2.
3.
4.
Find the movie with a row id of 6
Find the movies released in the years between 2000 and 2010
Find the movies not released in the years between 2000 and 2010
Find the first 5 Pixar movies and their release year
Lesson 3: Queries with constraints (Pt. 2)
1.
2.
3.
4.
Find all the Toy Story movies
Find all the movies directed by John Lasseter
Find all the movies (and director) not directed by John Lasseter
Find all the WALL-* movies
Lesson 4: Filtering and sorting Query results
1.
2.
3.
4.
List all directors of Pixar movies (alphabetically), without duplicates
List the last four Pixar movies released (ordered from most recent to least)
List the first five Pixar movies sorted alphabetically
List the next five Pixar movies sorted alphabetically
Review: Simple SELECT Queries
1.
2.
3.
4.
5.
List all the Canadian cities and their populations
Order all the cities in the United States by their latitude from north to south
List all the cities west of Chicago, ordered from west to east
List the two largest cities in Mexico (by population)
List the third and fourth largest cities (by population) in the United States and
their population
2
SQL Boat
Lesson 6: Multi-table queries with JOINs
1. Find the domestic and international sales for each movie
2. Show the sales numbers for each movie that did better internationally rather
than domestically
3. List all the movies by their ratings in descending order
Lesson 7: OUTER JOINs
1. Find the list of all buildings that have employees
2. Find the list of all buildings and their capacity
3. List all buildings and the distinct employee roles in each building (including
empty buildings)
Lesson 8: A short note on NULLs
1. Find the name and role of all employees who have not been assigned to a
building
2. Find the names of the buildings that hold no employees
Lesson 9: Queries with expressions
1. List all movies and their combined sales in millions of dollars
2. List all movies and their ratings in percent
3. List all movies that were released on even number years
Lesson 10: Queries with aggregates (Pt. 1)
1. Find the longest time that an employee has been at the studio
2. For each role, find the average number of years employed by employees in
that role
3. Find the total number of employee years worked in each building
Lesson 11: Queries with aggregates (Pt. 2)
1. Find the number of Artists in the studio (without a HAVING clause)
2. Find the number of Employees of each role in the studio
3. Find the total number of years employed by all Engineers
3
SQL Boat
Lesson 12: Order of execution of a Query
1. Find the number of movies each director has directed
2. Find the total domestic and international sales that can be attributed to each
director
Lesson 13: Inserting rows
1. Add the studio's new production, Toy Story 4 to the list of movies (you can use
any director)
2. Toy Story 4 has been released to critical acclaim! It had a rating of 8.7, and
made 340 million domestically and 270 million internationally. Add the record
to the BoxOffice table.
Lesson 14: Updating rows
1. The director for A Bug's Life is incorrect, it was actually directed by John
Lasseter
2. The year that Toy Story 2 was released is incorrect, it was actually released
in 1999
3. Both the title and director for Toy Story 8 is incorrect! The title should be "Toy
Story 3" and it was directed by Lee Unkrich
Lesson 15: Deleting rows
1. This database is getting too big, lets remove all movies that were released
before 2005.
2. Andrew Stanton has also left the studio, so please remove all movies directed
by him.
Lesson 16: Creating tables
Create a new table named Database with the following columns:
– Name A string (text) describing the name of the database
– Version A number (floating point) of the latest version of this database
– Download_count An integer count of the number of times this database was
downloaded
4
SQL Boat
Lesson 17: Altering tables
1. Add a column named Aspect_ratio with a FLOAT data type to store the aspectratio each movie was released in.
2. Add another column named Language with a TEXT data type to store the
language that the movie was released in. Ensure that the default for this
language is English.
Lesson 18: Dropping tables
1. We've sadly reached the end of our lessons, lets clean up by removing the
Movies table
2. And drop the BoxOffice table as well
5
SQL Boat
Solutions
Lesson 1: SELECT queries 101
1. SELECT title
FROM movies;
2. SELECT director
FROM movies;
3. SELECT title, director
FROM movies;
4. SELECT title, year
FROM movies;
5. SELECT *
FROM movies;
Lesson 2: Queries with constraints (Pt. 1)
1. SELECT *
FROM movies
WHERE id = 6;
2. SELECT *
FROM movies
WHERE year BETWEEN 2000 and 2010;
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SQL Boat
3. SELECT *
FROM movies
WHERE year NOT BETWEEN 2000 and 2010;
4. SELECT *
FROM movies
WHERE id BETWEEN 1 AND 5;
Lesson 3: Queries with constraints (Pt. 2)
1. SELECT *
FROM movies
WHERE title LIKE "%Toy Story%";
2. SELECT *
FROM movies
WHERE director = "John Lasseter";
3. SELECT *
FROM movies
WHERE director != "John Lasseter";
4. SELECT *
FROM movies
WHERE title LIKE "WALL-%";
7
SQL Boat
Lesson 4: Filtering and sorting Query results
1. SELECT DISTINCT director
FROM movies
ORDER BY director ASC;
2. SELECT *
FROM movies
ORDER BY year DESC
LIMIT 4;
3. SELECT *
FROM movies
ORDER BY title ASC
LIMIT 5;
4. SELECT *
FROM movies
ORDER BY title ASC
LIMIT 5
OFFSET 5;
Lesson 5 Review: Simple SELECT Queries
1. SELECT country, population
FROM north_american_cities
WHERE country = "Canada";
8
SQL Boat
2. SELECT city
FROM north_american_cities
WHERE country = "United States"
ORDER BY latitude DESC;
3. SELECT city
FROM north_american_cities
WHERE longitude < (
SELECT longitude
FROM north_american_cities
WHERE city = "Chicago"
)
ORDER BY longitude ASC;
4. SELECT city
FROM north_american_cities
WHERE country = "Mexico"
ORDER BY population DESC
LIMIT 2;
5. SELECT city, population
FROM north_american_cities
WHERE country = "United States"
ORDER BY population DESC
LIMIT 2
OFFSET 2;
9
SQL Boat
Lesson 6: Multi-table queries with JOINs
1. SELECT title, domestic_sales, international_sales
FROM movies
INNER JOIN boxoffice
ON movies.id = boxoffice.movie_id;
2. SELECT *
FROM movies
INNER JOIN boxoffice
ON movies.id = boxoffice.movie_id
WHERE international_sales > domestic_sales;
3. SELECT title, rating
FROM movies
INNER JOIN boxoffice
ON movies.id = boxoffice.movie_id
ORDER BY rating DESC;
Lesson 7: OUTER JOINs
1. SELECT DISTINCT building_name
FROM buildings
LEFT JOIN employees
ON buildings.building_name = employees.building
WHERE building IS NOT NULL;
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SQL Boat
2. SELECT *
FROM buildings;
3. SELECT DISTINCT building_name, role
FROM buildings
LEFT JOIN employees
ON buildings.building_name = employees.building;
Lesson 8: A short note on NULLs
1. SELECT *
FROM employees
LEFT JOIN buildings
ON employees.building = buildings.building_name
WHERE building_name IS NULL;
2. SELECT *
FROM buildings
LEFT JOIN employees
ON buildings.building_name = employees.building
WHERE role IS NULL;
11
SQL Boat
Lesson 9: Queries with expressions
1. SELECT
title,
(domestic_sales + international_sales)/1000000 AS sales
FROM boxoffice AS b
INNER JOIN movies AS m
ON m.id = b.movie_id;
2. SELECT
title,
rating*10 AS ratings_percent
FROM boxoffice AS b
INNER JOIN movies AS m
ON m.id = b.movie_id;
3. SELECT title, year
FROM boxoffice AS b
INNER JOIN movies AS m
ON m.id = b.movie_id
WHERE year % 2 = 0
ORDER BY year ASC;
Lesson 10: Queries with aggregates (Pt. 1)
1. SELECT MAX(years_employed) AS longest_years
FROM employees;
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SQL Boat
2. SELECT
role,
AVG(years_employed)AS average_years_employed
FROM employees
GROUP BY role;
3. SELECT
building,
SUM(years_employed)AS sum_of_years_employed
FROM employees
GROUP BY building;
Lesson 11: Queries with aggregates (Pt. 2)
1. SELECT COUNT(role)
FROM employees
WHERE role = 'Artist';
2. SELECT
role,
COUNT(name) AS number_of_employees
FROM employees
GROUP BY role;
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SQL Boat
3. SELECT
role,
SUM(years_employed)
FROM employees
GROUP BY role
HAVING role = "Engineer";
Lesson 12: Order of execution of a Query
1. SELECT
director,
COUNT(*)
FROM movies
GROUP BY director;
1. SELECT
director,
SUM(domestic_sales + international_sales) AS total_sales
FROM movies
INNER JOIN boxoffice
ON movies.id = boxoffice.movie_id
GROUP BY director;
Lesson 13: Inserting rows
1. INSERT INTO movies
(title, director, year, length_minutes)
VALUES
('Toy Story 4', 'Lance Lafontaine', 2984, 15);
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SQL Boat
2. INSERT INTO boxoffice
(movie_id, rating, domestic_sales, international_sales)
VALUES
(15, 8.7, 340000000, 270000000);
Lesson 14: Updating rows
1. UPDATE movies
SET director = "John Lasseter"
WHERE title = "A Bug's Life";
2. UPDATE movies
SET
title = 'Toy Story 3',
director = 'Lee Unkrich'
WHERE id = (
SELECT id
FROM movies
WHERE title = 'Toy Story 8'
);
Lesson 15: Deleting rows
1. DELETE FROM movies
WHERE year < 2005;
2. DELETE FROM movies
WHERE director = 'Andrew Stanton';
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SQL Boat
Lesson 16: Creating tables
CREATE TABLE IF NOT EXISTS Database (
Name TEXT,
Version FLOAT,
Download_count INTEGER
);
Lesson 17: Altering tables
1. ALTER TABLE movies
ADD aspect_ratio FLOAT;
2. ALTER TABLE movies
ADD language TEXT
DEFAULT 'English';
Lesson 18: Dropping tables
1. DROP TABLE IF EXISTS movies;
2. DROP TABLE IF EXISTS boxoffice;
16
Build Your First Project - Javascript
styles.css
h1{
text-align: center;
color: #FFD700;
margin-top: 50px;
}
index.html
<!DOCTYPE html>
<html lang="en">
<head>
<script src="index.js"></script>
<link
href="https://cdn.jsdelivr.net/npm/bootstrap@5.0.0beta3/dist/css/bootstrap.min.css"
rel="stylesheet"
integrity="sha384eOJMYsd53ii+scO/bJGFsiCZc+5NDVN2yr8+0RDqr0Ql0h+rP48ckxlpbzKgwra6"
crossorigin="anonymous">
<link href="styles.css" rel="stylesheet">
<title>First Project</title>
</head>
<body>
<div class="d-flex justify-content-center" style="margin-top:50px">
<button id="hello" class="btn btn-warning">Welcome!</button>
<button id="red" class="btn btn-danger">Red</button>
<button id="green" class="btn btn-success">Green</button>
<button id="blue" class="btn btn-primary">Blue</button>
</div>
<h1></h1>
</body>
</html>
2
Build Your First Project - Javascript
index.js
document.addEventListener('DOMContentLoaded', function(){
//Get the parameters in HTML
let sayhello = document.querySelector('h1');
let body = document.querySelector('body');
//Send a "Hello" message when click the button
document.querySelector('#hello').onclick = function() {
sayhello.innerHTML = 'Hello, you!';
body.style.backgroundColor = 'white';
};
//Change the background color to red when click the button
document.querySelector('#red').onclick = function() {
body.style.backgroundColor = 'red';
sayhello.innerHTML = '';
};
//Change the background color to green when click the button
document.querySelector('#green').onclick = function() {
body.style.backgroundColor = 'green';
sayhello.innerHTML = '';
};
//Change the background color to blue when click the button
document.querySelector('#blue').onclick = function() {
body.style.backgroundColor = 'blue';
sayhello.innerHTML = '';
};
});
3
TODO - Flask
application.py
from flask import Flask, redirect, render_template, request
app = Flask(__name__)
#Create this to have a list of todos
todos = []
@app.route("/")
def tasks():
return render_template("tasks.html", todos=todos)
@app.route("/add", methods=["GET","POST"])
def add():
#GET is a request method used by default
#And is used when you want to get a page
if request.method == "GET":
return render_template("add.html")
#POST means you're trying to send data to the server
else:
#Get the input from the user
todo = request.form.get('task')
#Add this new task to the todos list
todos.append(todo)
#Redirect the user to the page that has the todos
return redirect("/")
2
TODO - Flask
layout.html
<!DOCTYPE html>
<html lang="en">
<head>
<title>Tasks</title>
</head>
<body>
{% block body %}
{% endblock %}
</body>
</html>
tasks.html
{% extends "layout.html" %}
{% block body %}
<h1>Tasks</h1>
<ul>
{% for todo in todos %}
<li>{{ todo }}</li>
{% endfor %}
</ul>
<a href="/add">Create a New Task!</a>
{% endblock %}
3
TODO - Flask
add.html
{% extends "layout.html" %}
{% block body %}
<form action="/add" method="POST">
<input id="task" name="task" type="text" placeholder="Add New Task!">
<input id="submit" type="submit" disabled>
</form>
<script>
document.querySelector('#task').onkeyup = function() {
if (document.querySelector('#task').value === ''){
document.querySelector('#submit').disabled = true;
}
else{
document.querySelector('#submit').disabled = false;
}
}
</script>
{% endblock %}
4
TODO - Javascript
styles.css
h1{
text-align: center;
color: gray;
}
.container-style{
margin-bottom: 50px;
margin-left: 50px;
margin-right: 50px;
margin-top: 50px;
}
task.html
<!DOCTYPE html>
<html lang="en">
<head>
<!--Defines what the title of the webpage will be-->
<!--As displayed in the tab of the browser-->
<title>Tasks</title>
<!--Explains to the compiler where the javascript file code is-->
<script src="tasks.js"></script>
<!--Explains to the compiler where the css file is-->
<link href="styles.css" rel="stylesheet">
<!--Explains to the compiler where the Bootstrap documentation is-->
<link
href="https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/css/bootstrap.min.css"
rel="stylesheet">
</head>
2
TODO - Javascript
<body>
<!--Heading of the page-->
<div class="container-style">
<h1>Tasks</h1>
</div>
<div class="container">
<!--Creates an unordered list to display the tasks-->
<!--The javascript code will handle the list items-->
<ul id="tasks" class="list-group"></ul>
</div>
<!--Creates a form to the user inputs a new task-->
<div class="container-style">
<form>
<!--This input field is to type the new task-->
<input id="task" placeholder = "New Task" type="text" class="form-control">
<!--This input field is to create a submit button-->
<input id="submit" type="submit" class="btn btn-light">
</form>
</div>
</body>
</html>
3
TODO - Javascript
tasks.js
document.addEventListener('DOMContentLoaded', () => {
//Select the form tag in HTML to be used later
const form = document.querySelector('form');
//Select the ul tag in HTML to be used later
const ul = document.querySelector('ul');
//Select the submit button in HTML to be used later
const submit = document.querySelector('#submit');
//Select the task input in HTML to be used later
let newtask = document.querySelector('#task');
//Default action for the submit button when you enter on the page
submit.disabled = true;
//Listen for input to be typed into the input field
newtask.addEventListener('keyup', () => {
//When there is nothing typed in the input, turns the submit button disabled
if (newtask.value === '') {
submit.disabled = true;
}
//When there is something typed in the input, turns the submit button enable
else {
submit.disabled = false;
}
});
4
TODO - Javascript
//When submit the task
form.addEventListener('submit', (event) => {
//Prevents the default submission of the form which involves
//either reloading the current page or redirecting to a new one
event.preventDefault();
//We can create HTML elements using the createElement function
//Creates an list item on HTML
const li = document.createElement('li');
//Add newtask value in list item
li.innerHTML = newtask.value;
//We can then add HTML those elements to the DOM using the append function
//Append the list item to unordered list
ul.append(li);
//Clear the value of newtask variable and set it to empty
newtask.value = '';
//Disable button when there is nothing in newtask
submit.disabled = true;
});
});
5
TODO App Django
1. To start a new Django project, you must open the terminal of your computer (not
VS Code terminal), and run:
django-admin startproject NAME_OF_YOUR_PROJECT
2. Then, you open VS Code in the project’s folder you just created
3. In VS Code terminal you should create a new app to you project. So, run:
python manage.py startapp NAME_OF_YOUR_APP
4. To check if everything is working fine, run:
python manage.py runserver
5. If it displays the image above, you’re good to continue and you can close the
website.
6. Go to seetings.py and add the new app in your “installed_apps”. Let’s suppose
the app is called “tasks”.
7. Go to urls.py (in the same folder of your settings.py) and add the URL pattern to
your app.
8. Now, inside the folder of your app (the same folder that exists the views.py file),
you should create a new file called urls.py. In there, you’re going to create the
URL pattern for the first route of your app. Let’s suppose we are going to create
‘index’ route.
9. After creating the URL for the route, let’s create the function for that route in
your views.py.
10. Remember that in the index route you need:
a) You need a list that will be global to all your code (create this list
before the function index). This list will store all the tasks.
b) You need to render the index.html file
c) You need to pass your list from Python to HTML
11. Now it’s time to create your index.html inside the templates folder (remember
to create a templates folder!)
12. Remember that in the index.html you need:
a) There will be a h1
b) There will be an unordered list
c) Figure out how you’re going to display all the items of your list inside
the unordered list (remember the <li> tag)
13. Now let’s create our second route. First, create the URL pattern in your urls.py
14. Then, create the function for that route in your views.py
15. At this part, we will only work with the GET method, in the future we’re going to
work with the POST.
16. Remember that your route right now needs:
a) Check if it is a GET method
b) You need to render the add.html file
17. Now it’s time to create your add.html inside the templates folder
18. Remember that your add.html file need:
a) There will be a h1
b) There will be a form
c) There will be two inputs: one for the task (type=”text”) and another
for the button (type=”submit”)
19. Now let’s work with the POST method in add function (on views.py). Remember
that you will need:
a) Get the data from the form and store in a variable
b) Add the new task in your tasks list
c) Render the index.html file
d) You need to pass your list from Python to HTML
20. Finally, include the hyperlink to add page in your index.html
Checklist – Search (Project 0)
Summary
Pages........................................................................................................................................... 3
Query Text.................................................................................................................................. 4
Query Images............................................................................................................................ 5
Query Advanced....................................................................................................................... 6
Appearance ............................................................................................................................... 8
Lucky ........................................................................................................................................... 9
Aesthetics................................................................................................................................ 10
FAQ.............................................................................................................................................. 11
Important
Throughout this document there will be blue colored links.
These links will help you to solve the project.
Right-click and open in a new tab.
Disclaimer
This is a checklist to help you go through the problem.
The following checklist if for educational purposes only.
Cheating or any other activities are highly discouraged!
2
Checklist – Search (Project 0)
Pages
Specification
Your website should have at least three pages: one for Google Search, one for
Google Image Search, and one for Google Advanced Search.
How To Do This?
Since the project must have three pages and the distribution code already
given to us index.html, you have to create two more HTML files for the Google Image
Search and Google Advanced Search.
Specification
On the Google Search page, there should be links in the upper-right of the
page to go to Image Search or Advanced Search. On each of the other two pages,
there should be a link in the upper-right to go back to Google Search.
How To Do This?
To solve this problem, you can use the <ul> tag to create a navbar. This navbar
must contain 2 nav-item (in this case you can use the <li> tag) to redirect the site to
the other two pages that are not open.
For example, the Google search page must have two nav-item to redirect the
site to Image Search or Advanced Search, like indicated by the green arrows in the
image below.
The best way to do this is using the <a> tag, where the “href” is going to set the
HTML file you want to redirect when the user clicks in the text.
3
Checklist – Search (Project 0)
Query Text
Specification
On the Google Search page, the user should be able to type in a query, click
“Google Search”, and be taken to the Google search results for that page.
How To Do This?
The code already gives to us the <form> and the action with the corresponding
page that we are going find the result. We also have the two <input> tags that creates
the text input and the submit button.
Note that in the <input type=”text”> we have a property of name=”q” inside. The
action added with this name are going to redirect the page to the corresponding
result page right after the button submit is clicked. So, in this part you do not need to
do anything, the project already give this to us.
Specification
Like Google’s own, your search bar should be centered with rounded corners.
The search button should also be centered and should be beneath the search bar.
How To Do This?
To do this, it is recommended that you create a CSS file. You can find how to
do rounded corners using the CSS tools in this link:
https://www.w3schools.com/cssref/css3_pr_border-radius.asp
4
Checklist – Search (Project 0)
You can find how to align the elements in the Bootstrap documentation. We
suggest you to use the <input type=”submit”> inside a <div> tag to use the Bootstrap
class. Look on this link:
https://getbootstrap.com/docs/4.0/utilities/flex/
At this point, your project should look like this:
Query Images
Specification
On the Google Image Search page, the user should be able to type in a query,
click a search button, and be taken to the Google Image search results for that page.
How To Do This?
The first thing you have to do is to create a file similar to index.html, but the
difference in this case will be the <a> tag, because you have to redirect to Google
Search and Google Advanced Search.
For the image search you must use de Developer Tools to find how to do this
search. You are going to have to use an <input type=”hidden”> tag.
5
Checklist – Search (Project 0)
At this point, your project should look like this:
Query Advanced
On the Google Advanced Search page, the user should be able to provide input
for the following four fields (taken from Google’s own advanced search options).
Specification
Find pages with… “all these words:”
How To Do This?
On Google Advanced Search page, you should use the <input> tag and add the
name property like appears when you check the Developer Tools. The image below
shows the trick:
6
Checklist – Search (Project 0)
Specification
Find pages with… “this exact word or phrase:”
How To Do This?
On Google Advanced Search page, you should use the <input> tag and add the
name property like appears when you check the Developer Tools. The image below
shows the trick:
Specification
Find pages with… “any of these words:”
How To Do This?
On Google Advanced Search page, you should use the <input> tag and add the
name property like appears when you check the Developer Tools. The image below
shows the trick:
Specification
Find pages with… “none of these words:”
7
Checklist – Search (Project 0)
How To Do This?
On Google Advanced Search page, you should use the <input> tag and add the
name property like appears when you check the Developer Tools. The image below
shows the trick:
Appearance
Specification
Like Google’s own Advanced Search page, the four options should be stacked
vertically, and all the text fields should be left aligned.
How To Do This?
To stack the four options vertically in the Advanced Search page, you can use
one <div> tag for each input.
To do all the text fields left aligned, you can add in your CSS file a class setting
the margin-left size you want to have in your page.
At this point your project should look like this:
8
Checklist – Search (Project 0)
Specification
Consistent with Google’s own CSS, the “Advanced Search” button should be
blue with white text. When the “Advanced Search” button is clicked, the user should
be taken to search results page for their given query.
How To Do This?
To do this part, you can use the Bootstrap documentation about buttons. Look
on this link:
https://getbootstrap.com/docs/4.0/components/buttons/
Lucky
Specification
Add an “I’m Feeling Lucky” button to the main Google Search page. Consistent
with Google’s own behavior, clicking this link should take users directly to the first
Google search result for the query, bypassing the normal results page.
How To Do This?
On Google Search page, you should use the <input> tag and add the name
property like appears when you check the Developer Tools. The image below shows
the trick:
9
Checklist – Search (Project 0)
Aesthetics
Specification
The CSS you write should match Google’s own aesthetics as best as possible.
How To Do This?
We suggest you check the CSS and Bootstrap documentation. Also, use the
Developer Tools to know some interesting properties to be used in your project.
For example, if you want to know the margin, background and padding of the
original “Google Search” button, you can use the Developer Tools to check that.
.
10
Checklist – Search (Project 0)
FAQ
Question
Answer
Try searching for "CS50" on Google, then do the same on Google Images and
compare the URLs.
You will see the only difference between them is an additional parameter
called tbm, which Google uses to know it should display the Google Images results
instead of the Search results.
You need to use this parameter in project0 to redirect to the correct results
page.
Question
Answer
To do this you should use margin property of CSS and align elements property,
also from CSS. Check the link below:
11
Checklist – Search (Project 0)
https://www.w3schools.com/css/css_align.asp
Question
Answer
We already answer that in the Query Advanced section.
Question
Answer
We already answer that in the Query Advanced section.
12
First you must click in the link showed in the image below to authorize CS50:
Open the terminal in your VS Code and do the following commands:
1. To start your git:
git init
2. To send the code in the right path on GitHub, you have to do the next command
replacing branch_given_on_item_3_of_the_project with the name of the branch
that the requirements give to you. For example, for Project 0 you are going to use
web50/projects/2020/x/search
git checkout -b branch_given_on_item_3_of_the_project
3. This command will return you the status of your git, it’s important to check if you
are in the right track. You should see a message telling you about which branch
you are.
git status
4. This command will add all files to submit in the future.
git add -A
5. This command will return you the status of your git, it’s important to check if you
are in the right track. You should see all the files in green.
git status
6. Commit all files and add a message inside the quotation marks
git commit -am “some message you want to add”
7. This way you are going to put the files in the correct path on GitHub. Do not forget
to change USERNAME in the link below to your username on GitHub.
git remote add origin https://github.com/me50/USERNAME.git
8. Push your files to GitHub. After this command check your CS50.me to see if
everything went fine.
git push origin --all
1. Click on the third icon in your sidebar. When you are there, click on “Initialize
Repository”:
2. Add all the files you want to store in your GitHub by clicking on the plus sign (+). You
can click on one file at a time:
Or you can add all the files at the same time:
3. Once you added the files, there will be a new section for you called “Staged Changes”.
Now you can click in the check sign to commit the files:
4. You should add a message to this commit:
5. Click on “Publish Branch”:
6. It will appear this pop up to you where you can select if the repository will be private
or public:
7. Now your files are on GitHub!
Checklist – Wiki (Project 1)
Summary
Understanding Util.py............................................................................................................. 3
Convert Markdown to HTML................................................................................................. 4
Entry Page ................................................................................................................................. 5
Hint............................................................................................................................................... 7
Index Page................................................................................................................................. 7
Search......................................................................................................................................... 8
New Page................................................................................................................................. 10
Edit Page ...................................................................................................................................13
Random Page...........................................................................................................................16
FAQ..............................................................................................................................................17
Important
Throughout this document there will be blue colored links.
These links will help you to solve the project.
Right-click and open in a new tab.
Disclaimer
This is a checklist to help you go through the problem.
The following checklist if for educational purposes only.
Cheating or any other activities are highly discouraged!
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Understanding Util.py
list_entries()
Returns a list of all names of encyclopedia entries.
Let us look on how to use this function:
allEntries = util.list_entries()
Now, let us look on how the information that this function returns come to us
(using the debugger):
save_entry(title,content)
Saves an encyclopedia entry, given its title and Markdown content. If an
existing entry with the same title already exists, it is replaced.
Let us look on how to use this function:
util.save_entry(title,content)
get_entry(title)
Retrieves an encyclopedia entry by its title. If no such entry exists, the function
returns None.
Let us look on how to use this function:
entry = util.get_entry(title)
Now, let us look on how the information that this function returns come to us
(using the debugger):
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Convert Markdown to HTML
Specification
On each entry’s page, any Markdown content in the entry file should be
converted to HTML before being displayed to the user. You may use the pythonmarkdown2 package to perform this conversion, installable via pip3 install
markdown2.
How To Do This?
First you should understand what the python-markdown2 does. You can check
the link given to us in the specifications:
https://github.com/trentm/python-markdown2
Markdown is a light text markup language, and the entries are written in this
language. The problem of this project is that we are using HTML, that is another
markup language. How to solve this?
The link explains how we are going to do this. But just the link is not enough.
The first thing you must do is to import the markdown2 library in ‘views.py’.
Then, you are going to do this conversion every time you have to display the
page that already exists in the entries folder or every time you create a new page.
First, you are going to create a variable to store the ‘Markdown()’ function. This
function is going to do the conversion to you. For example:
markdown = Markdown()
But how am I going to take the markdown content of the entry?
To do this, you should use the ‘get_entry’ function, because it retrieves an
encyclopedia entry by its title. If no such entry exists, the function returns None.
Thus, you are going to store in a variable the entry using the ‘get_entry’
function. For example:
entry = util.get_entry(entry_name)
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If the ‘get_entry’ function returns None, you are going to return None in your
conversion.
If the ‘get_entry’ function does not return None, you are going to create a new
variable to store this conversion. In this variable, you are going to use the explanation
in the link. Thus, you are going to do the following.
html_converted = markdown.convert(entry)
It is scary for the first time, but you are going to see that this will save you
time!
Entry Pages
Specification
Visiting /wiki/TITLE, where TITLE is the title of an encyclopedia entry, should
render a page that displays the contents of that encyclopedia entry.
How To Do This?
To solve this, you should go to urls.py file and add in the urlpatters a new path.
Look at Lecture Django in CS50 notes and check the ‘greet’ function. You
should understand the flexible way that they use to create a path (image below):
Thus this new path will be something like ‘/wiki/<str: title>’, where the ‘title’
will the title of an encyclopedia entry.
Specification
The view should get the content of the encyclopedia entry by calling the
appropriate util function.
How To Do This?
To solve this, you should go to views.py file and add a new route.
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Look at Lecture Django in CS50 notes and check the ‘greet’ function. You
should understand how they use the <str:name> from url in the route (image below):
With the ‘title’ in hands, you can call the appropriate util function.
In the entry page, you want to display the content of the title. You should use
the logic to convert the Mardown to HTML.
Specification
If an entry is requested that does not exist, the user should be presented with
an error page indicating that their requested page was not found.
How To Do This?
Like explained in the previous bullet point, the ‘get_entry’ retrieves an
encyclopedia entry by its title. If no such entry exists, the function returns None. Thus,
your ‘conversion Markdown to HTML’ returns or the HTML content or None.
Knowing that, you should do an if-else condition in your route (views.py file)
using the None as this condition.
If ‘conversion Markdown to HTML’ returns None, you should display a page
indicating that the entry does not exists.
You can create a new HTML file to display just this error message and indicate
in the route to render that specific page.
Specification
If the entry does exist, the user should be presented with a page that displays
the content of the entry. The title of the page should include the name of the entry.
How To Do This?
If ‘conversion Markdown to HTML’ does not return None, you should display
the entry page. To do this, you should pass as context the title and the conversion to
HTML to render the html file.
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Look at Lecture Django in CS50 notes and check the ‘greet’ function. You
should understand how they pass the context from Django to HTML (image below):
Hint
Specification
By default, when substituting a value in a Django template, Django HTMLescapes the value to avoid outputting unintended HTML. If you want to allow for an
HTML string to be outputted, you can do so with the safe filter (as by adding |safe
after the variable name you’re substituting).
How To Do This?
You probably had this issue when trying to render your entry page. If you do
not use this ‘save’ property in the HTML file, the compiler will understand that you
are passing a string and not a html content.
To solve this, use the value of the conversion to html and the safe word
together. For example:
{{ conversion_html | safe }}
Index Page
Specification
Update index.html such that, instead of merely listing the names of all pages
in the encyclopedia, user can click on any entry name to be taken directly to that
entry page.
How To Do This?
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To solve this, you should go to ‘index.html’ file and you are going to find
basically all done for you. The only thing that you have to add is an <a> tag to solve
this ‘click on any entry name to be taken directly to that entry page’.
Final Step
You should go to ‘layout.html’ and add <a> tag to the user be able to click in
‘Home’ and go to the index page.
Search
Specification
Allow the user to type a query into the search box in the sidebar to search for
an encyclopedia entry.
How To Do This?
To solve that, you should create a new URL simple path in ‘urls.py’. Like the
following image from Lecture Django in CS50 notes.
In addition, you should create a new route in ‘views.py’. In there, you should
use the ‘list_entries’ function the way that we recommended in the beginning of this
checklist.
Then, you should get the input from the user in the search box and store in a
variable. Since this is a request GET method, you should use, for example:
search = request.GET(‘NameOfTheInputOnHTML’)
To check if there is an entry with the title that the user wants to search, you
should use the ‘get_entry’ function the way that we recommended in the beginning of
this checklist.
Specification
If the query matches the name of an encyclopedia entry, the user should be
redirected to that entry’s page.
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How To Do This?
This will occur if the function ‘get_entry’ does not return None.
Then, you should render the entry page of this entry searched.
Specification
If the query does not match the name of an encyclopedia entry, the user should
instead be taken to a search results page that displays a list of all encyclopedia
entries that have the query as a substring. For example, if the search query were ‘Py’,
then ‘Python’ should appear in the search results.
How To Do This?
This will occur if the function ‘get_entry’ returns None.
You should create an empty list. Then, you should do an iteration in each entry
in the ‘list.entries’ and check if the search is a substring of the entries that already
exists.
If the search is a substring, you are going to append this entry in the empty
list that you created previously. Else, you go to the next iteration.
After all, pass as context this new list and render the ‘index.html’ page with
this context.
This is what your project should return when you seach ‘Py’ in the entries.
Specification
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Clicking on any of the entry names on the search results page should take the
user to that entry’s page.
How To Do This?
Since you are using the index.html file to render the search query, you do not
need to do this step, because you already did in the Index section.
New Page
Specification
Clicking “Create New Page” in the sidebar should take the user to a page
where they can create a new encyclopedia entry.
How To Do This?
You should go to ‘layout.html’ and add <a> tag to the user be able to click in
‘Create New Page’ and go to the create new page.
You should create a new URL and new route to display this page.
Also, you should create a html file to display the components of your page.
After that, in the ‘views.py’ render the page.
Specification
Users should be able to enter a title for the page and, in a textarea, should be
able to enter the Markdown content for the page.
How To Do This?
In the html file, you are going to use the <form> tag to create the textarea for
title and content of the page.
You can set how many rows your textarea will display. Look at this link:
https://www.w3schools.com/tags/tag_textarea.asp
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Since you are using form with Django, you must use the syntax explained in
Lecture Django in CS50 notes. Look the image below:
Inside the form, you should use two <textarea> tags, one for title and other for
Markdown content. The title will be the title of your tab (green arrow in the image
below) and the Markdown content will be the content displayed in your page (yellow
arrow in the image below).
Specification
Users should be able to click a button to save their new page.
How To Do This?
After creating the <textarea> tags and before closing the <form> tag, use an
<input> tag with ‘type=submit’.
You can change the style of this button using Bootstrap for example. See the
following link:
https://getbootstrap.com/docs/5.0/components/buttons/
At this point, the New Page should be look like:
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Specification
When the page is saved, if an encyclopedia entry already exists with the
provided title, the user should be presented with an error message.
Otherwise, the encyclopedia entry should be saved to disk, and the user should
be taken to the new entry’s page.
How To Do This?
Now you are going to work with the ‘views.py’ file. In there, you have to do an
if-else condition to check if you are going to work with the POST method or GET
method. You can use the following notation:
if request.method == ‘POST’:
else:
The POST method basically will handle the data of the form. Inside this if, you
are going to get the information from the form using the following notation, for
example:
title = request.POST[‘title’]
content = request.POST[‘content’]
Then, you have to check if the entry already exists. To do this, you can use the
‘get_entry’ function that we explained in the Util section.
If the ‘get_entry’ does not return None, you should render a html file saying
that this page already exists. Here you are going to do the same way as we explained
in the Entry Page section.
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If the ‘get_entry’ returns None, you are going to call the conversion to HTML
function and render the entry page.
The GET method basically will handle displaying the ‘New Page’ html file. Thus,
inside of the else you are just going to render the ‘New Page’.
Edit Page
Specification
On each entry page, the user should be able to click a link to be taken to a
page where the user can edit that entry’s Markdown content in a textarea.
How To Do This?
You should create a new URL path and a new route. These two files will be like
the entry page, but in this case the URL should be like ‘edit/<str: title>/’.
To solve this, you can add an <a> tag that redirect the user to this new URL
path.
You can style that using buttons from Bootstrap. See the following link:
https://getbootstrap.com/docs/5.0/components/buttons/
To create a button in your <a> tag you should copy the class from Bootstrap
and put inside de <a> tag. For example:
<a class=”btn btn-primary” href=’…’>
At this point, your entry page should look like this:
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Specification
The textarea should be pre-populated with the existing Markdown content of
the page. (i.e., the existing content should be the initial value of the textarea).
How To Do This?
Now you are going to work with the ‘views.py’ file. In there, you have to do an
if-else condition to check if you are going to work with the POST method or GET
method. You can use the following notation:
if request.method == ‘GET’:
else:
The GET method basically will handle displaying the ‘Edit Page’ HTML file.
To pre-populate with the existing Markdown content of the page, you should
use the ‘get_entry’ function.
Then, you need to pass the entry name and the entry content as context from
‘views.py’ to ‘edit’ HTML.
In the ‘edit’ HTML, you are going to use the <form> tag to create the textarea
for title and content of the page.
You can set how many rows your textarea will display. Look at this link:
https://www.w3schools.com/tags/tag_textarea.asp
Since you are using form with Django, you must use the syntax explained in
Lecture Django in CS50 notes. Look the image below:
So far, the page should look like:
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Note that the title will be the title of your tab (green arrow in the image below)
and the Markdown content will be the content displayed in your page (yellow arrow
in the image below).
Specification
The user should be able to click a button to save the changes made to the
entry.
How To Do This?
Your <input type=”submit”> will be this button to save the changes made to the
entry. You can style this input using Bootstrap:
https://getbootstrap.com/docs/5.0/components/buttons/
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This information will be sent to the backend (‘views.py’). In the route you
already have the GET method. Now we are going to work with the POST method.
The POST method basically will handle the data of the form. Inside this else,
you are going to get the information from the form using the following notation, for
example:
title = request.POST[‘title’]
content = request.POST[‘content’]
Then, you must save this entry using the ‘save_entry’ function. Check the
‘Understand util.py’ section.
After saving, you should convert this edited entry using the ‘conversion
Markdown to HTML’.
Specification
Once the entry is saved, the user should be redirected back to that entry’s
page.
How To Do This?
This is the last part in the POST method. You are going to render the page with
the edited entry. Remember to pass as context the title and the content of the edited
entry.
Random Page
Specification
Clicking “Random Page” in the sidebar should take user to a random
encyclopedia entry.
How To Do This?
You should create a new url and new route to display this page.
You can use the ‘random library, because there is a function ‘randpm.choice()’
that pick a random entry in the list you pass as input.
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After that, call the conversion to HTML function and render the page.
Final Step
You should go to ‘layout.html’ and add <a> tag to the user be able to click in
‘Random Page’ and go to the random page.
FAQ
Question
How To Do This?
The reason why the search is not working is because the code didn’t have the
{csrf_token}. Check the Search section to know better.
Question
How To Do This?
When you do the iteration in each entry to if the search input is a substring of
other entries, you have to make all lower case.
To do this, you can use the .lower() Python function to do the comparison. For
example:
if search.lower() in entry.lower():
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Question
How To Do This?
Check the Edit Page section and you will understand how to do it.
Question
How To Do This?
To solve the formatting of <textarea> tags you should change the properties in
styles.css.
To solve the markdown conversion, look at Convert Markdown to HTML section
and the New Page section.
Question
How To Do This?
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Check the Edit Page section and you will understand how to do it.
Question
How To Do This?
To solve this, you should go to ‘index.html’ file and you are going to find
basically all done for you. The only thing that you have to add is an <a> tag to solve
this ‘click on any entry name to be taken directly to that entry page’.
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Summary
Models........................................................................................................................................................3
Create Listing..........................................................................................................................................3
Active Listings Page .............................................................................................................................6
Listing Page .............................................................................................................................................7
Watchlist ................................................................................................................................................. 18
Categories .............................................................................................................................................. 19
Django Admin Interface.................................................................................................................... 20
FAQ........................................................................................................................................................... 20
Important
Throughout this document there will be blue colored links.
These links will help you to solve the project.
Right-click and open in a new tab.
Disclaimer
This is a checklist to help you go through the problem.
The following checklist if for educational purposes only.
Cheating or any other activities are highly discouraged!
2
Checklist – Commerce (Project 2)
Models
Specification
Your application should have at least three class in addition to the User model:
one for auction listings, one for bids, and one for comments made on auction listings.
It’s up to you to decide what fields each model should have, and what the types of
those fields should be. You may have additional class if you would like.
How To Do This?
To solve this problem, we suggest to first understand what models do. Look at
CS50 Web Lecture 4 Notes in the section Django Models:
https://cs50.harvard.edu/web/2020/notes/4/
Basically, you can create Django models to work with databases instead of
directly using SQL queries.
In the Lecture 4, they suggest creating a file called ‘models.py’ where you are
going to outline what data you want to store in your application. Then, Django will
determine the SQL syntax necessary to store information on each of your class.
Thus, before starting the project 2, make sure you really understand the Flight
example gave in CS50 Web Lecture 4 Notes.
After understanding the Flight example, you will be very comfortable working
with models in your project. This models specification will be done while you progress
in your project. Let’s go to the next part!
Create Listing
Specification
Users should be able to visit a page to create a new listing. They should be
able to specify a title for the listing, a text-based description, and what the starting
bid should be. Users should also optionally be able to provide a URL for an image for
the listing and/or a category (e.g. Fashion, Toys, Electronics, Home, etc.).
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How To Do This?
Since the new listing information will be stored in the database, you can
create a Model to do this. Look at CS50 Web Lecture 4 Notes to have an idea on how
to do this:
You are going to do something like this in your ‘models.py’, but in your case
you should fulfill the requirements for the listing: title, text-based description,
starting bid, image by URL and/or category. Check the link below to know better how
to create each field for the class:
https://docs.djangoproject.com/en/3.0/ref/forms/fields/#built-in-field-classes
We suggest creating one model for the listing and one model for the category.
Note: remember to create a field for the owner of the listing!
After creating your class, you should create an URL path, a route, and a HTML
file to create a new listing.
In the new HTML file, you should use a <form> tag and have as input the
requirements said above.
Note: since you are using forms with Django, you must use the syntax
explained in Lecture 3 Django in CS50 notes. Look at the image below:
Now you are going to work with the ‘views.py’ file. In there, you have to do an
if-else condition to check if you are going to work with the POST method or GET
method. You can use the following notation:
if request.method == ‘POST’:
else:
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The POST method basically will handle the data of the form. Inside of this if,
you are going to get the information from the form using the following notation, for
example:
title = request.POST[‘title’]
…
category = request.POST[‘category’]
You can fulfill the model using the notation explained in the Lecture 4 (all in
one line). Look how it is done in CS50 Web Lecture 4 Notes.
Or you can create the Flight class in views.py by creating a variable to store
the model itself. For example:
flight = Flight()
Then you can store each field of the class using the dot operator. For example,
if you want to assign a value to the origin field in the Flight class, you can do the
following:
flight.origin = “New York”
After you’ve set all the fields you call flight.save() and the data will be stored
in the database.
The GET method basically will handle displaying the ‘New Listing Page’ html
file. Thus, inside of the else you are just going to render the HTML file you already
created (the one with the <form> tag).
Active Listings Page
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Specification
The default route of your web application should let users view all of the
currently active auction listings. For each active listing, this page should display (at
minimum) the title, description, current price, and photo (if one exists for the listing).
How To Do This?
To solve this problem, you should work with the ‘index.html’ file and use the
Bootstrap tools to create a nice ‘Active Listings Page’. You may be interested in use
<div> tag to separate each listing information in boxes, like the image below:
In ‘models.py’ you should create a field in your listing model to set if the listing
is active or not. By now, all your listing should be active. Further in the project, you
will be able to change this status.
In ‘views.py’ you should find a way to display only the active listings. To do this,
you should manipulate your class. Look how it works in CS50 Web Lecture 4 Notes.
In your case, you should filter by the active field.
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Look at Lecture Django in CS50 notes and check the ‘greet’ function. You
should understand how they pass the context from Django to HTML (image below):
After passing as context this information from ‘views.py’ to the HTML file, you
are going to display the title, description, current price, and photo (if one exists for
the listing). For example, passing the listing as context in the ‘views.py’:
Listings = Listings.objects.filter(active=True)
In ‘index.html’, since you are passing multiple listings, you should do an
iteration to display all listings at a time. For example:
{% for listing in listings %}
…
{% endfor %}
Remember to use the double curly braces to display the information from
‘views.py’ in the HTML file. For example, to display the title of the listing you can use:
{{ listing.title }}
Listing Page
Specification
Clicking on a listing should take users to a page specific to that listing. On that
page, users should be able to view all details about the listing, including the current
price for the listing.
How To Do This?
To do this, in your ‘index.py’, you should use an <a> tag in each listing in your
index. The <a> tag should have as ‘href’ the URL for the listing.
This URL for the listing will be like what you did in Wiki Project. Look at greet
function in CS50 Web Lecture 3 Notes:
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Note: in this case you should use <int:listing_id> instead of <str:name>.
In this page, you should pass the information from de backend (‘views.py) to
the frontend (HTML file).
In ‘views.py’ you should find a way to display only the active listings. To do this,
you should manipulate your class. Look how it works in CS50 Web Lecture 4 Notes.
In your case, you should filter the category model by the listing field and the
listing model you should get by the id. If you do not remember how to do this, look at
‘Active Listings Page’ section.
Thus, in this page you are going to display the following information:
• Name of the listing: you should display the title of the listing. For example:
{{ listing.title }}
• The image of the listing: it is optional. You are going to display this using the
<img> tag and the image is stored in the same way you have the title. For
example:
{{ listing.image }}
• The description of the listing: you can do the same way as you did for name of
the listing.
• Category of the listing: you can do the same way as you did in name of the
listing, but in this case, you should call the category that you passed as
context. For example:
{{ category.title }}
• The current bid: you are going to display the same way as you display the
name of the listing.
It is up to you decide how many information you want to display from your
Listing class.
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Note: now you know that you are going to have a starting bid and a current bid
in your listing. Thus, we recommend creating one field for each of these bids.
Specification
If the user is signed in, the user should be able to add the item to their
“Watchlist.” If the item is already on the watchlist, the user should be able to remove
it.
How To Do This?
In this case you should pass a Boolean saying whether the listing of a
particular user is in his watchlist as context in your ‘views.py’.
Look at Lecture Django in CS50 notes and check the ‘greet’ function. You
should understand how they pass the context from Django to HTML (image below):
It might be useful to use the Python in operator.
In the HTML file, you first should check if the user is signed in. To do this, you
can do an if-else condition. For example:
{% if user.is_authenticated %}
…
{% else %}
…
{% endif %}
Inside the if user.is_authenticated, you are going to create a condition based
on this context that you passed. If this condition is True, you are going to display the
logic to remove the listing from the watchlist. If the condition is False, you are going
to display the logic to add the listing to the watchlist. For example, the in_watchlist
is a Boolean variable that stores whether a listing is in the user’s watchlist:
{% if in_watchlist == True %}
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…
{% else %}
…
{% endif %}
Inside these if-else condition, you can display a button, for example. When the
user clicks on this button, the user can add or remove the listing to his watchlist.
To handle adding the listing in the watchlist, you should create a new URL path
and a new route in ‘views.py’. This URL will be like what you did in ‘Listing Page’. Look
at greet function in CS50 Web Lecture 3 Notes:
Note: in this case you should use <int:listing_id> instead of <str:name>.
In the route, you should get the listing by id. With this id you can get the listing
in the Listing model and add the user in the watchlist field.
You can fulfill the model using the notation explained in the Lecture 4 (all in
one line). Look how it is done in CS50 Web Lecture 4 Notes.
Or you can create the Flight class in views.py by creating a variable to store
the model itself. For example:
flight = Flight()
Then you can store each field of the class using the dot operator. For example,
if you want to assign a value to the origin field in the Flight class, you can do the
following:
flight.origin = “New York”
After you’ve set all the fields you call flight.save() and the data will be stored
in the database.
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Remember how you did in ‘Create Listing’ section!
To handle the removal of the listing from the watchlist, you should create a
new URL path and a new route in ‘views.py’. This URL will be like what you did in
‘Listing Page’. Look at greet function in CS50 Web Lecture 3 Notes:
Note: in this case you should use <int:listing_id> instead of <str:name>.
In the route, you should get the listing by id. With this id you can get the listing
in the Listing model and remove the user in the watchlist field. You can remove
checking the .remove property in the following link:
https://docs.djangoproject.com/en/3.1/topics/db/queries/
You can fulfill the model using the notation explained in the Lecture 4 (all in
one line). Look how it is done in CS50 Web Lecture 4 Notes.
Or you can create the Flight class in views.py by creating a variable to store
the model itself. For example:
flight = Flight()
Then you can store each field of the class using the dot operator. For example,
if you want to assign a value to the origin field in the Flight class, you can do the
following:
flight.origin = “New York”
After you’ve set all the fields you call flight.save() and the data will be stored
in the database.
Remember how you did in ‘Create Listing’ section and ‘Adding to Watchlist’!
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Specification
If the user is signed in, the user should be able to bid on the item. The bid must
be at least as large as the starting bid, and must be greater than any other bids that
have been placed (if any). If the bid doesn’t meet those criteria, the user should be
presented with an error.
How To Do This?
You can create a new model in ‘models.py’ for Bids. In this model should have
as fields the offer, the user that gave the bid and the listing (where the offer was
made).
In the listing HTML file, you should first check if the user is authenticated and
if the listing is active. For example, where the listing.active is a Boolean variable that
sets whether the listing is active or not:
{% if user.is_authenticated and listing.active == True %}
…
{% else %}
…
{% endif %}
Inside the if user.is_authenticated and listing.active == Ture, you are going to
use a <form> tag and have as input the bid of the user.
Note: since you are using form with Django, you must use the syntax explained
in Lecture 3 Django in CS50 notes. Look the image below:
To handle submitting the bid, you should create a new URL. This URL will be
like what you did in ‘Listing Page’. Look at greet function in CS50 Web Lecture 3 Notes:
Note: in this case you should use <int:listing_id> instead of <str:name>.
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Then, you should create a new route for the comment. In this route you should
get the listing by the id. Look how it works in CS50 Web Lecture 4 Notes.
In there, you must do an if condition to check if you are going to work with the
POST method. You can use the following notation:
if request.method == ‘POST’:
The POST method basically will handle the data of the form. Inside this if, you
are going to get the information from the form using the following notation, for
example:
user_bid = request.POST[‘user_bid’]
Then, you must check if the user_bid is greater than the starting bid or the
current bid.
If is not, you should present an error for the user. You can do this by creating
a new HTML file for example.
If the offer is greater than the current bid or the start bid, you should add this
new bid in the model.
You can fulfill the model using the notation explained in the Lecture 4 (all in
one line). Look how it is done in CS50 Web Lecture 4 Notes.
Or you can create the Flight class in views.py by creating a variable to store
the model itself. For example:
flight = Flight()
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Then you can store each field of the class using the dot operator. For example,
if you want to assign a value to the origin field in the Flight class, you can do the
following:
flight.origin = “New York”
After you’ve set all the fields you call flight.save() and the data will be stored
in the database.
At this point, your project should look like:
Specification
If the user is signed in and is the one who created the listing, the user should
have the ability to “close” the auction from this page, which makes the highest bidder
the winner of the auction and makes the listing no longer active.
How To Do This?
In this case you should pass a Boolean saying whether the particular user is
the owner of the listing as context in your ‘views.py’.
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You can do this by checking if the user is the field that you created in your
Listing model to handle storing the owner of each listing. Thus, you should pass as
context your Boolean variable.
Look at Lecture Django in CS50 notes and check the ‘greet’ function. You
should understand how they pass the context from Django to HTML (image below):
In the HTML file, you first should check if the user is signed in. To do this, you
can do an if-else condition. For example:
{% if user.is_authenticated %}
…
{% else %}
…
{% endif %}
Inside the if user.is_authenticated, you are going to create a condition based
on this context that you passed. If this condition is True, you are going to display the
logic to close the bid.
Also, you must check if the listing is active or not. For example, the is_owner
is a Boolean variable that stores whether the user is the owner of the listing, and the
listing.active is a Boolean variable that stores whether the listing is active or not:
{% if is_owner == True and listing.active == True%}
…
{% else %}
…
{% endif %}
Inside this if condition, you can display a button, for example. When the user
clicks on this button, the user can close the auction.
To handle closing the listing, you should create a new URL path and a new
route in ‘views.py’. This URL will be like what you did in Listing Page. Look at greet
function in CS50 Web Lecture 3 Notes:
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Checklist – Commerce (Project 2)
Note: in this case you should use <int:listing_id> instead of <str:name>.
In the route, you should get the listing by id. With this id you can get the listing
in the Listing model and set the active field as False.
You can fulfill the model using the notation explained in the Lecture 4 (all in
one line). Look how it is done in CS50 Web Lecture 4 Notes.
Or you can create the Flight class in views.py by creating a variable to store
the model itself. For example:
flight = Flight()
Then you can store each field of the class using the dot operator. For example,
if you want to assign a value to the origin field in the Flight class, you can do the
following:
flight.origin = “New York”
After you’ve set all the fields you call flight.save() and the data will be stored
in the database.
Remember how you did in ‘Create Listing’ section!
Specification
If a user is signed in on a closed listing page, and the user has won that
auction, the page should say so.
How To Do This?
In this case you should pass a Boolean saying whether the particular user has
the current bid in a listing (the one that won the auction) as context in your ‘views.py’.
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You can do this by checking if the user is the field that you created in your
Listing model to handle storing the user that placed the current bid of each listing.
Thus, you should pass as context your Boolean variable.
Look at Lecture Django in CS50 notes and check the ‘greet’ function. You
should understand how they pass the context from Django to HTML (image below):
In the HTML file, you first should check if the user is the buyer of the listing
and the listing is not active.
For example, the is_winner is a Boolean variable that stores whether the user
is the winner of the listing, and the listing.active is a Boolean variable that stores
whether the listing is active or not:
{% if listing.active == False and is_winner == True %}
…
{% endif %}
Inside the if, you are going to display a message telling the user that he won
the auction.
Specification
Users who are signed in should be able to add comments to the listing page.
The listing page should display all comments that have been made on the listing.
How To Do This?
About the comments, you can create a new model. In this model should have
as fields the comment, the user that gave the comment and the listing (where the
comment was made).
In this section, we must do two things. First receive new comments from the
user and second display the comments.
1. Receive new comments from the user:
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In the listing HTML file, you are going to first check if the user is authenticated.
For example:
{% if user.is_authenticated %}
…
{% else %}
…
{% endif %}
Inside the if user.is_authenticated, you are going to use a <form> tag and have
as input the comment of the user.
Note: since you are using form with Django, you must use the syntax explained
in Lecture 3 Django in CS50 notes. Look the image below:
To handle submitting the comments, you should create a new URL. This URL
will be similar to what you did in Listing Page. Look at greet function in CS50 Web
Lecture 3 Notes:
Note: in this case you should use <int:listing_id> instead of <str:name>.
Then, you should create a new route for the comment. In this route you should
get the listing by the id. Look how it works in CS50 Web Lecture 4 Notes.
In there, you have to do an if condition to check if you are going to work with
the POST method. You can use the following notation:
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Checklist – Commerce (Project 2)
if request.method == ‘POST’:
The POST method basically will handle the data of the form. Inside this if, you
are going to get the information from the form using the following notation, for
example:
user_comment = request.POST[‘user_comment’]
Then, you should add this information to the Comment model.
You can fulfill the model using the notation explained in the Lecture 4 (all in
one line). Look how it is done in CS50 Web Lecture 4 Notes.
Or you can fulfill the model creating a variable to store the model itself. For
example:
flight = Flight()
Then, instead of doing what is in the image above, you can store each field of
the model by calling the previous variable and using a dot and the name of the field.
For example, if you want to fulfill the origin field in Flight class, you can do the
following:
flight.origin = “New York”
Now, you should do the same idea in your project.
2. Display the comments in the listing:
In the listing page route, you should pass as context the comments for that
listing. Remember to use the following:
comments = Comment.objects.filter(listing=listing)
Look at Lecture Django in CS50 notes and check the ‘greet’ function. You
should understand how they pass the context from Django to HTML (image below):
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Since you are passing multiple listings, you should do an iteration to display
all the comments at a <div> tag. For example:
{% for comment in comments %}
…
{% endfor %}
Remember to use the double curly braces to display the information from
‘views.py’. For example, to display the comment you can use:
{{ comment.user }}
Watchlist
Specification
Users who are signed in should be able to visit a Watchlist page, which should
display all of the listings that a user has added to their watchlist. Clicking on any of
those listings should take the user to that listing’s page.
How To Do This?
To solve this, first you should pass the user watchlist model to a new HTML
file. You can do this by passing as context. Look at greet function on CS50 Web Lecture
3 Notes:
In this HTML file you are going to display the listings the same way as you did
in the ‘index.html’.
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Categories
Specification
Users should be able to visit a page that displays a list of all listing categories.
Clicking on the name of any category should take the user to a page that displays all
of the active listings in that category.
How To Do This?
To solve this, first you should pass the category model to a new HTML file. You
can do this by passing as context. Look at greet function on CS50 Web Lecture 3
Notes:
Then, you are going to the HTML file and can create a <form> tag to display the
categories options.
Note: since you are using form with Django, you must use the syntax explained
in Lecture 3 Django in CS50 notes. Look the image below:
The form will be handled in a new route, where you are going to display the
specific listings of that category chosen by the user.
Thus, in this new route you should get the values from the form. And then, use
this category to get the listings. Pass this information to the HTML file. Remember
how to do this in the previous sections.
In this HTML file you are going to display the listings the same way as you did
in the ‘index.html’.
Django Admin Interface
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Specification
Via the Django admin interface, a site administrator should be able to view,
add, edit, and delete any listings, comments, and bids made on the site.
How To Do This?
To solve this, you are going to follow the steps explained in the ‘Django Admin’
at the end of CS50 Web Lecture 4 Notes. Just follow the steps!
FAQ
Specification
When should I use the @login_required decorator in my ‘views.py’?
How To Do This?
You should use this decorator any time you want display the page only if the
user is logged in. For example, you can use this @login_required decorator in the
watchlist page.
Specification
How should I create my Category model?
How To Do This?
Your Category model should have at least two fields. One for the name of the
category, and in this case, you are going to use the CharField.
The other field should have a relationship with the Listing model. In this case,
you should use the ForeignKey field.
Specification
When should I use the ManyToManyField relationship in ‘models.py’?
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How To Do This?
By default, this table name is generated using the name of the many-to-many
field and the name of the table for the model that contains it.
You should use the ManyToManyField in the watchlist for example. Because
this field will store which users wants to have in the watchlist for each listing.
Thus, you are going to be able to store multiple users in each listing.
For example, Mary and John want to have the Chocolate listing in the
watchlist. Mary wants to have the Cake listing in the watchlist. Daniel wants to have
Ice Cream listing in the watchlist. The ManyToManyField will store this information.
Specification
How To Do This?
The Bids model should store the data about the offer, the user that gave the
offer and a relation between the bid and the listing where the bid was placed.
This relation will be handled by the ForeignKey field.
Specification
How To Do This?
You should create a field in your Listing model to check if the listing is active
or not. You can do this by using the BooleanField.
Then, in your ‘views.py’ you must filter the listing by this Boolean. For example:
listings = Listing.objects.filter(active=True)
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Specification
How To Do This?
Since you are receiving the image by it is URL, you can display the image just
using the <img> tag and in the property ‘src’ you call the listing image. For example:
<img src={{ listing.image }}>
Remember to pass as context to the HTML file the Listing model. If you do not
know how to do this, check the ‘Listing Page’ section.
Look at Lecture Django in CS50 notes and check the ‘greet’ function. You
should understand how they pass the context from Django to HTML (image below):
Specification
How To Do This?
Look on how to do this in the ‘Watchlist’ section. You should pass the watchlist
as context from ‘views.py’ to the HTML file.
Look at Lecture Django in CS50 notes and check the ‘greet’ function. You
should understand how they pass the context from Django to HTML (image below):
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Checklist – Mail (Project 3)
Summary
Mail Project ............................................................................................................................... 3
Send Mail ................................................................................................................................... 3
Mailbox ....................................................................................................................................... 4
View Email ................................................................................................................................. 7
Archive and Unarchive ........................................................................................................ 10
Reply........................................................................................................................................... 11
CSS............................................................................................................................................. 14
FAQ............................................................................................................................................. 14
Important
Throughout this document there will be blue colored links.
These links will help you to solve the project.
Right-click and open in a new tab.
Disclaimer
This is a checklist to help you go through the problem.
The following checklist if for educational purposes only.
Cheating or any other activities are highly discouraged!
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Checklist – Mail (Project 3)
Mail Project
The distribution code gives to us all the backend done, so the only files that
you are going to work will be the inbox.js, inbox.html and styles.css.
Remember that the JavaScript will be written in the inbox.js; the HTML will be
written in the inbox.html; and the CSS will be in the styles.css.
Send Mail
Specification
When a user submits the email composition form, add JavaScript code to
actually send the email.
How To Do This?
To solve this bullet point you can create a new function with purpose of
submitting the email.
You should get the values of recipients, subject, and body from the input that
the user gives to the web app. To do this, take a look at this property of JavaScript:
https://www.w3schools.com/jsref/met_document_queryselector.asp
Specification
You’ll likely want to make a POST request to /emails, passing in values for
recipients, subject, and body.
How To Do This?
If you take a look at the API in the Mail Project explanation, you are going to
find a section called “POST/emails”. The CS50’s staff explain how you should send the
information that you are receiving from the frontend to the backend.
You basically are going to get the JavaScript code that they give to you and
make some changes.
We recommend you understand what fetch does before starting this part of
the project.
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Checklist – Mail (Project 3)
Specification
Once the email has been sent, load the user’s sent mailbox.
How To Do This?
To solve this, you should call the function load_mailbox, that is already made
to us in the distribution code and sending as input to the function the mailbox ‘sent’.
We recommend you use the setTimeout in order to wait the fetch call works.
This is interesting to be used because when you use fetch it takes a while to send and
receive the information, so the setTimeout will wait this information go and come to
render the page.
HINT
You are going to notice that if you try to send an email your page is not going
to be redirected to sent mailbox, but to inbox instead. How to solve this?
You should use the preventDefault function because this function will prevent
the default of submit to be refreshing the button.
Mailbox
Specification
When a user visits their Inbox, Sent mailbox, or Archive, load the appropriate
mailbox.
How To Do This?
To solve this problem, you are going to work with the load_mailbox function
that was already initialized for you in the distribution code.
Specification
You’ll likely want to make a GET request to /emails/<mailbox> to request the
emails for a particular mailbox.
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How To Do This?
If you take a look at the API in the Mail Project explanation, you are going to
find a section called “GET/emails/<str:mailbox>”. The CS50’s staff explain how you
should send the information that you are receiving from the frontend to the backend.
You basically are going to get the JavaScript code that they give to you and
make some changes.
We recommend you understand what fetch does before starting this part of
the project.
Specification
When a mailbox is visited, the application should first query the API for the
latest emails in that mailbox.
How To Do This?
This part is already done for you. If you take a look at mailbox route in
views.py, you are going to find on line 95 that the distribution code already returns
the email for the frontend in reverse chronological order.
Specification
When a mailbox is visited, the name of the mailbox should appear at the top
of the page (this part is done for you).
How To Do This?
As the specification already says, this part is done for you.
Specification
Each email should then be rendered in its own box (e.g. as a <div> with a
border) that displays who the email is from, what the subject line is, and the
timestamp of the email.
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Checklist – Mail (Project 3)
How To Do This?
To do this you should create a new function to render in each email its own
box.
PS: When you do the fetch call in the load_mailbox, we recommend you
remember to call this new function inside.
In this function you should do an iteration to work with one email at a time.
We recommend you look at forEach JavaScript property.
After that, you should get the values of recipient, subject and timestamp that
were passed from the backend to the frontend. Store these values in variables.
We recommend using the createElement property to create a new tag in the
HTML file using JavaScript in order to display this information that you grabbed from
the backend.
Use the property innerHTML to display this information in the new tag that you
created.
To complete this task, you have to append the new tag that you created in
JavaScript at an existing tag in the HTML file.
Specification
If the email is unread, it should appear with a white background. If the email
has been read, it should appear with a gray background.
How To Do This?
At this point of the problem, you should create an if-else condition to check if
the email was already read. If this is true, use the style.backgroundColor to set the
email background as gray. Else, use the same property to set the email background
as white.
At this point you project should look like this:
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View Email
Specification
When a user clicks on an email, the user should be taken to a view where they
see the content of that email.
How To Do This?
In the function that you just created to render in each email its own box, you
should use the addEventListener function to be triggered when the user clicks in the
email box.
Specification
You’ll likely want to make a GET request to /emails/<email_id> to request the
email.
How To Do This?
If you take a look at the API in the Mail Project explanation, you are going to
find a section called “GET/emails/100”. The CS50’s staff explain how you should send
the information that you are receiving from the frontend to the backend.
You basically are going to get the JavaScript code that they give to you and
make some changes.
We recommend you understand what fetch does before starting this part of
the project.
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Inside the fetch, you can call another function to display the email with the
specifications that are in the next bullet point.
Specification
Your application should show the email’s sender, recipients, subject,
timestamp, and body.
How To Do This?
This part you should do in your function created to display the email. To solve
this bullet point, you can grab the current email’s properties by the values that you
are grabbing from the fetch call.
For example, to grab the sender you can do email.sender and store this value
in a variable.
To display these values, you should use the property innerHTML in the div tag
that you include in your inbox.html.
Specification
You’ll likely want to add an additional div to inbox.html (in addition to emailsview and compose-view) for displaying the email. Be sure to update your code to hide
and show the right views when navigation options are clicked.
How To Do This?
The first thing you should do is adding a new div tag in inbox.html with an id
property.
To solve this, look at the function compose_email. You are going to find 3 lines,
which the first is the following comment:
// Show compose view and hide other views
The other 2 lines are the ones that you have to understand. When you use
document.querySelector(‘#id’).style.display you are using JavaScript to set if you
want to hide or not the components in that id attribute.
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When you set this to ‘none’, you are hiding the components in the HTML of that
id attribute.
When you set this to ‘block’, you are showing the components in the HTML of
that id attribute.
Specification
See the hint in the Hints section about how to add an event listener to an HTML
element that you’ve added to the DOM.
How To Do This?
In the function that you just created to render in each email its own box, you
should use the addEventListener function to be triggered when the user clicks in the
email box.
Specification
Once the email has been clicked on, you should mark the email as read. Recall
that you can send a PUT request to /emails/<email_id> to update whether an email is
read or not.
How To Do This?
We recommend creating a new function to mark the email as read.
If you take a look at the API in the Mail Project explanation, you are going to
find a section called “PUT/emails/<int:email_id>”. The CS50’s staff explain how you
should send the information that you are receiving from the frontend to the backend.
You basically are going to get the JavaScript code that they give to you and
make some changes.
We recommend you understand what fetch does before starting this part of
the project.
Instead of using ‘archived: true’ in the example that they gave to us, you should
use ‘read: true’.
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You are going to have to call this function in the display email function.
Remember that you only can set if the email was read or not if you are in the inbox
or archive mailbox.
At this point your project should look like this:
Archive and Unarchive
Specification
Allow users to archive and unarchive emails that they have received.
How To Do This?
You should create a new function to solve this issue. Basically, you are going
to use the addEventListener to trigger the fetch call after clicking the submit button.
In the next bullet points we explain better.
Specification
When viewing an Inbox email, the user should be presented with a button that
lets them archive the email. When viewing an Archive email, the user should be
presented with a button that lets them unarchive the email. This requirement does
not apply to emails in the Sent mailbox.
How To Do This?
To solve that you should create a button in your display email function. This
button will represent the archive/unarchive.
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Since this requirement does not apply to emails in the Sent mailbox, you are
going to call the function that handle with showing the archive button. The same way
as you did before for the mark email as read.
Specification
Recall that you can send a PUT request to /emails/<email_id> to mark an email
as archived or unarchived.
How To Do This?
If you take a look at the API in the Mail Project explanation, you are going to
find a section called “PUT/emails/<int:email_id>”. The CS50’s staff explain how you
should send the information that you are receiving from the frontend to the backend.
You basically are going to get the JavaScript code that they give to you and
make some changes.
We recommend you understand what fetch does before starting this part of
the project.
Specification
Once an email has been archived or unarchived, load the user’s inbox.
How To Do This?
After doing the fetch call, remember to call the load_mailbox function to
redirect the user to the inbox.
We recommend you use the window.location.reload() after redirecting the
user to the inbox.
Reply
Specification
Allow users to reply to an email. When viewing an email, the user should be
presented with a “Reply” button that lets them reply to the email.
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How To Do This?
You can do this by adding a <button> tag in the inbox.html.
Specification
When the user clicks the “Reply” button, they should be taken to the email
composition form.
How To Do This?
In the function that you created the display email, you are going to use the
addEventListener to trigger the compose_email function after clicking the submit
button. In the next bullet points we explain better.
Basically, the compose_email function just handle with the situation that you
are creating a new email to someone. Since this case is a reply, you should create a
new function.
After creating this function, you should go to compose_email and create an ifelse condition. This will make your compose_email be used in the reply button and in
the compose mailbox.
Specification
Pre-fill the composition form with the recipient field set to whoever sent the
original email.
How To Do This?
You can pre-fill the composition form by grabbing the current email’s
properties by the values that you are passing as input in this function.
For example, to grab the recipient you can do ‘email.sender’ and store this
value in a variable.
After that, you can use document.querySelector(‘#compose-recipients’).value
and set this value as the same of the variables.
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Specification
Pre-fill the subject line. If the original email had a subject line of foo, the new
subject line should be Re: foo. (If the subject line already begins with Re: , no need to
add it again.)
How To Do This?
You can pre-fill the composition form by grabbing the current email’s
properties by the values that you are passing as input in this function.
For example, to grab the subject you can do ‘Re: email.subject’ and store this
value in a variable.
After that, you can use document.querySelector(‘#compose-subject’).value
and set this value as the same of the variables.
Specification
Pre-fill the body of the email with a line like "On Jan 1 2020, 12:00 AM
foo@example.com wrote:" followed by the original text of the email.
How To Do This?
You can pre-fill the composition form by grabbing the current email’s
properties by the values that you are passing as input in this function.
For example, to grab the body with the timestamp you can do `On
${email.timestamp} ${email.sender} wrote: ${email.body}.’ and store this value in a
variable.
After that, you can use document.querySelector(‘#compose-body’).value and
set this value as the same of the variables.
At this point your project should look like this:
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CSS
Specification
You have to create your own style for this project.
How To Do This?
We recommend you use CSS and Bootstrap tools.
For example, to create the boxes separating each email, you can use padding
and border properties.
For example, to make the buttons look nice, you can use the Bootstrap buttons.
FAQs
Specification
How To Do This?
If your Javascript changes aren't being reflected in your site, check:
https://stackoverflow.com/questions/8392441/stop-chrome-caching-my-js-files
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Specification
How To Do This?
This issue happens in the function that handles with submitting the email.
You are going to notice that if you try to send an email your page is not going
to be redirected to Sent mailbox, but to inbox instead. How to solve this?
You should use the preventDefault function because this function will prevent
the default of submit to be refreshing the button.
Specification
How To Do This?
Replace line number 26 in mail/models.py with:
"timestamp": self.timestamp.strftime("%b %d %Y, %I:%M %p"),
This error is caused because strftime function implementation depends on
your operating system.
If you are Mac and Linux user, you will not have this problem.
If you are windows user, you should change the line 26 in models.py to the
following line.
"timestamp": self.timestamp.strftime("%b %#d %Y, %#I:%M %p"),
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Checklist – Mail (Project 3)
Specification
How To Do This?
When you are testing the ‘send email’ code, remember that you must send an
email to someone that is already registered in your backend.
Do not forget to create two users in the webapp and then send email to each
other.
Specification
How To Do This?
You should listen for an click or submit event on the submit button of the form
(#send) rather than form submission.
Also remember to use the preventDefault() to prevent form submission.
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