CS 180 Problem Solving and Object Oriented
Programming
Fall 2011
http://www.cs.purdue.edu/homes/apm/courses/CS180Fall2011/
Notes for Week 3:
September 5-9, 2011
Aditya Mathur
Department of Computer Science
Purdue University
West Lafayette, IN, USA
This week:
1. Quiz
2. Questions/Review
3. Writing simple programs
to solve simple problems
Readings and Self-help Exercises for Week 3
Readings:
Chapter 3: 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7
Self help Exercises [Not to be turned in]:
3.1, 3.2, 3.3, 3.7, 3.8, 3.23.
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Announcements
Feast with faculty: To resume on September 14.
Monday lecture by Dr Korb. Type conversions and handling
strings.
Project 1 deadline Friday September 23, 201.
Late submission is not in your best interest.
Programs in the textbook are now available for you
to download and play with. Go to the course web
site and click on the link marked Textbook Programs
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Programming Competition
Please send me (apm@cs.purdue.edu) mail to
register. I need names of the team members and of
the team leader.
Winning team gets a free:
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Questions?
Frequency Code for your iClicker: AA
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Quiz
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Q1. The value of a will be 0 after which one
of the following assignments?
(a) float a=(float)1/2;
(b) float a=1/2;
(c ) int a=1/2;
Correct answer: c
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Q2. Which one of the following is not a
primitive type in Java?
(a) int
(b) Float
(c) float
(d) double
Correct answer: b
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Q3. What is the value of the expression 7%2?
(a) 1
(b) 0
(c) 2
(d) 3
Correct answer: a
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Q4. Given int a=4; what is the value of the
expression a<<2?
(a) 8
(b) 16
(c) 32
(d) 64
Correct answer: b
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Let us write a simple Java program:
The problem
Write a Java program to compute the
net sale in dollars given the price of
each ticket in dollars and the number
of tickets sold.
Assume that a randomly selected
discount of between 3 to 7% is given
on any sale.
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Problem: Understanding
This is an easy problem!
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Problem: Design of solution
Keep this step independent of Java!
Step 1: Get data [price of a ticket and total tickets sold]
Step 2: Compute total sale[multiply the items input]
Step 3: Find discount to be given [3 to 7%]
Step 4: Compute discounted sale price [=total sale-(total
sale*discount)].
Step 5: Display the discounted sale price.
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Problem: Refine solution: Get data
Keep this step independent of Java!
Step 1.1: Prompt for price
Step 1.2: Read price
Step 1.3: Prompt for number of tickets sold
Step 1.4: Read number of tickets sold
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Problem: Refine solution: Compute total sale
Keep this step independent of Java!
Step 2: Compute
Total sale=price of a ticket * number of tickets sold
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Problem: Refine solution: Compute discount
Keep this step independent of Java!
Step 3: Generate a random number (say, r) between 0 and 1
and convert this to a number (say, d) between 3 and 7.
d=mr+c [Remember the straight line y=mx+c?]
d
7
m= ?
c= ?
3
0
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Problem: Refine solution: Compute discounted
price
Keep this step independent of Java!
Step 4: Compute
discounted price= total price-(total
price*discount)
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Problem: Refine solution: Display discounted price
Keep this step independent of Java!
Step 5: Display discounted price (as easy as
that!!).
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Code the solution in Java.
Test it.
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Week 3: September 5-9, 2011
Hope you enjoyed this week!
Questions?
Contact your recitation instructor. Make
full use of our office hours.
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