Python List While Loop

Python List While Loop

Python List is a collection of items. While loop can be used to execute a set of statements for each of the element in the list.

In this tutorial, we will learn how to use While loop to traverse through the elements of a given list.

Syntax of List While Loop

Elements of list are ordered. So, we can access the elements using index. We will make use of this property to traverse through items of list using while loop.

In general, the syntax to iterate over a list using while loop is

index = 0
while index < len(myList):
    element = myList[index]
    #statement(s)
    index += 1

where

• element contains value of the this element in the list. For each iteration, next element in the list is loaded into this variable with the changing index.
• myList is the Python List over which we would like to traverse through.
• statement(s) are block are set of statement(s) which execute for each of the element in the list.

Examples

1. Iterate over a list of strings using While loop

In this example, we will take a list of strings, and iterate over each string using while loop, and print the string length.

myList = ['pineapple', 'banana', 'watermelon', 'mango']

index = 0
while index < len(myList):
    element = myList[index]
    print(len(element))
    index += 1

Output

9
6
10
5

Reference tutorials for the above program

• Python print()
• Python len()

2. Iterate over a list of numbers using While loop

In this example, we will take a list of numbers, and iterate over each number using while loop, and in the body of while loop, we will check if the number is even or odd.

myList = [5, 7, 8, 3, 4, 2, 9]

index = 0
while index < len(myList):
    element = myList[index]
    if element % 2 == 0:
        print('even')
    else:
        print('odd')
    index += 1

Output

odd
odd
even
odd
even
even
odd

Reference tutorials for the above program

• Python If-Else
• Python print()

Summary

In this tutorial of Python Examples, we learned how to use While Loop to iterate over Python List elements.