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Python While Loop

Python While Loop Tutorial

In this tutorial, you will learn about Python while loop using an appropriate example. Python while is used, when you want to execute a block of code for a number of times.
In previous we have seen details about Python if-else statement using appropriate syntax and examples. To learn Python if else statement click here.

Before going through this tutorial let’s see what exactly about while loop in Python and why you need to use while loop in Python?

What is Python while loop ?

Python While loop is a loop that is used to execute a set of statements as long as the condition is True.
In the while loop when the test expression evaluates True then execute the body of the while loop and if the test expression is evaluated false then exit the loop.

Why should be using Python while loop ?

Sometimes we want to execute a block of code for a specific number of times, Then while loop in Python is the best way at that time.

Syntax of while loop in Python.

while test expression:
	body of while

In the above Python while loop syntax first checks the condition and enters the body when the condition becomes True and if the condition is False then exit the loop.

Python while loop Example:

To understand the python while loop we take a suitable example that better understands you.

def counter():
	i = 0
	while i < 10:
		print("i is ",i)
		i = i + 1
		
counter()

Output

i is  0
i is  1
i is  2
i is  3
i is  4
i is  5
i is  6
i is  7
i is  8
i is  9

In the above example create a function counter and inside the function define a variable i which initial value is 0.
print the value of i as long as the condition is true when the condition will false loop will be terminated.

While loop with else statement.

Python provides a facility to use else keyword with a while loop. Sometimes we need to print some message just end after the while loop execution then we can use the else keyword.

let’s understand how we can use else keyword with python while loop.

Example

def calculator():
	i = 1
	while i < 11:
		print("Condition true")
		i = i + 1	
	else:
		print("execution is finished")
calculator()

Output

Condition true
Condition true
Condition true
Condition true
Condition true
Condition true
Condition true
Condition true
Condition true
Condition true
execution is finished

In the above example, print Condition true as long as condition will True and also print the execution is finished message after the end of while loop execution.

Python while loop with a break statement:

To stop the execution even if the condition is True in python while loop, use the break statement. break statement define in python while loop with the break keyword

Example

counter = 1
while counter < 10:
	print("counter")
	if counter == 5:
		break
	counter = counter + 1

Output

counter
counter
counter
counter
counter

In the above example counter is initialized with value one and checking the condition, if the value of the counter will less than 10 then the print counter and if the value counter will equal to five, Then loops will terminate.

Python while loop with continue statement:

To stop the current iteration and continue with the next iteration in python while loop, use the continue statement.

Example

counter = 0
while counter < 10:
	counter = counter + 1
	if counter == 5:
		continue
	print(counter)

Output

1
2
3
4
6
7
8
9
10

Conclusion:

So, In this article, you have learned what is Python while loop and how to use while loop in Python to execute a block of code for a specific number of times.

Sometimes we want to write a program who perform a task as long as the condition is True, Then while loop in Python loop fulfill that feature

I think this will helped you. if you like this post please comment and share with your friends who want to learn programming from scratch.

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