CS110
Date:
TA:
Email:
09/22/2004
Kosta Kleisouris
kkonst@paul.rutgers.edu, http://paul.rutgers.edu/~kkonst
Chapter 2
1. In True Basic there are 2 types of variables:
a. Variables for numbers, eg: X, Y, height, age
b. Variables for strings, eg: name$, country$
2. A string is a sequence of characters that is surrounded by quotes, e.g.: “Jim”, “USA”, “324”. So,
variables for strings have a dollar sign at the end, whereas variables for numbers don’t.
3. Statements covered in chapter 2: REM, END, INPUT, READ/DATA, PRINT
4. REM: is used to insert remarks in a program
a. You can also insert a remark at the end of a line, by typing an exclamation mark and then the
remark
5. END: shows the end of a program. Every True basic program has to have and END statement
6. INPUT, INPUT PROMPT: they are used when we would like the user to supply some values. The
syntax is as follows:
a. INPUT variables separated by commas
b. INPUT PROMPT “the prompt”: variables separated by commas
7. READ/DATA: they are used as a pair to assign values to variables. The difference between INPUT
or INPUT PROMT and READ/DATA is that with the INPUT, INPUT PROMPT statements the
program stops and asks the user to supply values for some variables, whereas with the READ/DATA
the values are built into the program. The syntax is as follows:
a. READ variables separated by commas
DATA values separated by commas
b. Common syntax errors: Not enough data, Wrong type of data
8. PRINT: is used to display information on the screen of the computer. The syntax is:
a. PRINT list
The list consists of numbers, strings, variables or mathematical expressions separated by
commas or semicolons.
Example #1: Prints employees’ checks
REM Section C7
REM Name: John Smith
REM Program: 2-10
REM Date: 06/07/04
REM TA name: Ann Patterson
INPUT PROMPT “Give me your name”: name$
INPUT PROMPT “What is today’s date?”: dt$
INPUT PROMPT “What is your salary?”: salary
PRINT dt$
PRINT “Pay “;name$;” a check made out for $”;salary
END
-----------OUTPUT ---------------------Give me your name Peter Rodriguez
What is today’s date? 06/07/04
What is your salary? 50000
06/07/04
Pay Peter Rodriguez a check made out for 50000
Example #2
REM Shopping a bicycle
READ shipping, tax
DATA 20, 50 !shipping cost and taxes
PRINT “How much does this bicycle cost? ”;
INPUT cost
PRINT “The total cost is “;cost+shipping+tax
END
---------------- OUTPUT ----------------How much does this bicycle cost? 200
The total cost is 270
Chapter 3
1. So far, we have used INPUT, INPUT PROMPT and READ/DATA to assign values to variables.
These statements don’t give us the flexibility to combine values in order to create new values. For
instance, we might want to calculate some values based on some values that the user has supplied. A
statement that does numerical calculations is LET.
Syntax:
LET variable-name = equation
How it works:
The equation is reduced down to a single value that is assigned to the
variable on the left of the equal sign. If the equation contains other
variables, these variables are replaced by their values.
2. Variable names consist of letters and numbers, but the first character of the variable name is always a
letter. You can also use an underline ( _ ) in a variable name, but no space. Finally, all the statements
of True Basic (READ, DATA, INPUT etc), can not be used as variable names.
3. How do we combine values in calculations in order to create new values? The following
mathematical operations are available:
 Addition (+)
 Division (/)
 Subtraction (-)
 Exponentiation (^)
 Multiplication (*)
 Grouping ()
Example #1
READ pi, diam
DATA 3.14, 10
LET circlearea = pi*(diam/2)^2
PRINT “The area of the circle is “;circlearea
END
Example #2
LET kount = 1
LET kount = kount + 4
LET kount = (kount – 2)/2
PRINT “The value of kount is “;kount
END
Example #3
READ apple_bcost, orange_bcost, banana_bcost
DATA 1.3, 1.2, 1.1
! dollars per pound that a store pays to buy a particular type of fruit
LET apple_scost = apple_bcost*1.5
!selling cost of apples
LET orange_scost = orange_bcost*1.5
!selling cost of oranges
LET banana_scost = banana_bcost *1.5
!selling cost of bananas
INPUT PROMPT “How many pounds of apples do you want ?” : apple_pounds
INPUT PROMPT “How many pounds of oranges do you want ?”: orange_pounds
INPUT PROMPT “How many pounds of bananas do you want ?”: banana_pounds
LET cost = apple_pounds*apple_scost + orange_pounds*orange_scost + banana_pounds*banana_scost
PRINT “Customer has to pay $“;cost
END
Example #4
INPUT PROMPT “What is the length of the room ?”:length
INPUT PROMPT “What is the width of the room ?”:width
LET roomarea = length*width
PRINT “The area of the room is “;roomarea
END
Example #5 (2 Syntax Errors)
LET K = 9
LET K – 1 = X
LET Y = ( (X + 2)* 2/4
PRINT Y
END
Assignments for Next Week: 75-5, 89-6
Note for problem 89-6: the last sentence of this problem may lead you to believe a conditional IF-THEN
statement is needed; you don’t need such a statement. The output is just a number and a statement.