Python Tutorial

Python While Loop

What is While Loop in Python?

In the Python programming language, a while loop statement runs a target statement repeatedly as long as a specific condition is true.

Syntax

while expression:

    statement(s)

Example:

#!/usr/bin/python

count = 0

while (count < 7):

   print( 'The count is:', count)

   count = count + 1

print ("bye bye!")

Output:

The count is: 0
The count is: 1
The count is: 2
The count is: 3
The count is: 4
The count is: 5
The count is: 6
bye bye!

The Infinite Loop in Python

If a condition is never FALSE, a loop becomes endless. While loops should be used with caution since it's possible that this condition will never resolve to a FALSE value. As a result, a never-ending cycle is created. An endless loop is a name given to such a loop.

Example:

var = 1

while var == 1 :  # This constructs an infinite loop

    num = input("Enter a number:")

    print ("You entered: ", num)

print ("Good bye!")

Output:

Enter a number: 20

You entered: 20

Enter a number: 29

You entered: 29

Enter a number: 3

You entered: 3

.

.

.

.

.

Example:

while True :  # This constructs an infinite loop

    num = input("Enter a number:")

    print ("You entered: ", num)

print("Good bye!")

Output:

Enter a number: 20
You entered: 20
Enter a number: 29
You entered:  29
Enter a number: 3
You entered: 3
.
.

While loop with else

Python enables you to use an else statement with a loop statement. When using the else statement with a while loop, it is performed when the condition turns false.

Example:

count = 0

while count < 5:

   print (count, "is  less than 5" )

   count = count + 1

else:

   print(count, "is not less than 5")

Output:

0 is less than 5
1 is less than 5
2 is less than 5
3 is less than 5
4 is less than 5
5 is not less than 5
Did you find this article helpful?