1. INPUT & VARIABLES

2. CMPF 144-Fundamental of Computing Theory (Python)
Input & Variables
Input -
1. The process of entering information into a computer.
2. The information entered or put into a computer for processing.
CMPF 144-Fundamental of Computing Theory (Python)

3. CMPF 144-Fundamental of Computing Theory (Python)
Input & Variables
This is what you type in your PC :
print "Halt!"
s = raw_input("Who Goes there? ")
print "You may pass,", s
variable
CMPF 144-Fundamental of Computing Theory (Python)

4. CMPF 144-Fundamental of Computing Theory (Python)
Input & Variables
When you ran the program, here is what your screen showed:
OUTPUT :
Halt!
Who Goes there? Josh
You may pass, Josh
input
CMPF 144-Fundamental of Computing Theory (Python)

5. CMPF 144-Fundamental of Computing Theory (Python)
Input & Variables
When you ran the program you probably noticed how you had to type in your name and
then press Enter. Then the program printed out some more text and also your name. This is an example of input.
CMPF 144-Fundamental of Computing Theory (Python)

6. CMPF 144-Fundamental of Computing Theory (Python)
Input & Variables
Variables are like a box that can store some
piece of data.
Next is a program to show examples of variables:
Josh
CMPF 144-Fundamental of Computing Theory (Python)

7. CMPF 144-Fundamental of Computing Theory (Python)
Input & Variables
SAMPLE PROGRAM 1
a = 123.4
b23 = ’Spam’
first_name = "Bill"
b = 432
c = a + b
print "a + b is", c
print "first_name is", first_name
print "Sorted Parts, After Midnight or",b23
OUTPUT :
a + b is 555.4
first_name is Bill
Sorted Parts, After Midnight or Spam
CMPF 144-Fundamental of Computing Theory (Python)

8. CMPF 144-Fundamental of Computing Theory (Python)
Input & Variables
123.4
Spam a
b23
Bill
432 c
first_name b
CMPF 144-Fundamental of Computing Theory (Python)

9. CMPF 144-Fundamental of Computing Theory (Python)
Input & Variables
Strings are a sequence of letters, numbers and other characters.
Example :
Spam , Bill ,a + b is ,first_name is - string
123.4 , number
CMPF 144-Fundamental of Computing Theory (Python)

10. CMPF 144-Fundamental of Computing Theory (Python)
Input & Variables
SAMPLE PROGRAM 2
a = 1
print a
a = a + 1
a = a * 2
OUTPUT : 1 2 4
CMPF 144-Fundamental of Computing Theory (Python)

11. CMPF 144-Fundamental of Computing Theory (Python)
Input & Variables a
2 X 2 = 4 1 a a
1 + 1 = 2
print a
print a + 1
print a X 2
CMPF 144-Fundamental of Computing Theory (Python)

12. CMPF 144-Fundamental of Computing Theory (Python)
Input & Variables
SAMPLE PROGRAM 3
num = input("Type in a Number: ")
str = raw_input("Type in a string:")
print "num =", num
print "num * 2 =",num*2
print "str =", str
print "str * 2 =",str*2
OUTPUT :
Type in a Number: 12.34
Type in a String: Hello
num = 12.34
num * 2 = 24.68
str = Hello
str * 2 = HelloHello
CMPF 144-Fundamental of Computing Theory (Python)

13. CMPF 144-Fundamental of Computing Theory (Python)
Input & Variables
num variable gets data from input
str variable gets data from raw_input
If you want the user to type in a number use input because it returns a number
If you want the user to type in a string use raw_input because it returns a string
CMPF 144-Fundamental of Computing Theory (Python)

14. CMPF 144-Fundamental of Computing Theory (Python)
Input & Variables
Numbers are of type int or float (which are short for ’integer’ and ’floating point’ respectively)
Strings are of type string
Integers and floats can be worked on by mathematical functions, strings cannot.
CMPF 144-Fundamental of Computing Theory (Python)

15. CMPF 144-Fundamental of Computing Theory (Python)
Input & Variables
SAMPLE PROGRAM 4
#This programs calculates rate and distance problems
print "Input a rate and a distance"
rate = input("Rate:")
distance = input("Distance:")
print "Time:",distance/rate
OUTPUT :
Input a rate and a distance
Rate:5
Distance:10
Time: 2
CMPF 144-Fundamental of Computing Theory (Python)

16. CMPF 144-Fundamental of Computing Theory (Python)
Input & Variables 5
rate
distance 10
10 / 5 = 2
time = distance/rate
CMPF 144-Fundamental of Computing Theory (Python)

17. CMPF 144-Fundamental of Computing Theory (Python)
Input & Variables
SAMPLE PROGRAM 4 (with error)
#This programs calculates rate and distance problems
print "Input a rate and a distance"
rate = raw_input("Rate:")
distance = input("Distance:")
print "Time:",distance/rate
string could not worked on by mathematical functions
Note : raw_input uses to get data in string type
CMPF 144-Fundamental of Computing Theory (Python)

18. CMPF 144-Fundamental of Computing Theory (Python)
Input & Variables
SAMPLE PROGRAM 5
#This program calculates the perimeter and area of a rectangle
print "Calculate information about a rectangle"
length = input("Length:")
width = input("Width:")
print "Area",length*width
print "Perimeter",2*length+2*width
OUTPUT :
> python area.py
Calculate information about a rectangle
Length:4
Width:3
Area 12
Perimeter 14
CMPF 144-Fundamental of Computing Theory (Python)

19. CMPF 144-Fundamental of Computing Theory (Python)
Input & Variables
SAMPLE PROGRAM 6
#Converts Fahrenheit to Celsius
temp = input("Farenheit temperature:")
print (temp-32.0)*5.0/9.0
OUTPUT :
> python temperature.py
Farenheit temperature:32
0.0
Farenheit temperature:-40
-40.0
Farenheit temperature:212
100.0
CMPF 144-Fundamental of Computing Theory (Python)