while loop

A while loop is a looping statement used to repeatedly execute a block of code as long as a specified condition remains True.

Unlike the for loop, the while loop is mainly used when we do not know exactly how many times the loop should repeat.

Explanation

• A while loop repeats a block of code continuously until the condition becomes False.

  The loop first checks the condition.

  • If the condition is True → loop executes
  • If the condition is False → loop stops

Step-by-Step Explanation of the Flowchart

1. Loop Start

The program starts the loop.

Initialization usually happens before the loop begins.

Example:

count = 1

2. Condition Check

The diamond shape checks the condition.

Example:

count <= 5

Two possibilities occur:

3. Condition is True

If the condition is True:

• The body of the while loop executes.
• The statements inside the loop run.

Example:

print(count)

4. Return Back to Condition

After executing the loop body:

• Control goes back to the condition.
• The condition is checked again.

Usually the variable is updated.

Example:

count = count + 1

This process keeps repeating.

5. Condition is False

When the condition becomes False:

• The loop stops.
• Control moves outside the loop.

6. Loop End

The loop terminates completely.

The next statements after the loop will execute.

Real-Life Scenario

• Enter password until it is correct
• Playing a game until lives become 0
• Filling water until the tank is full

 Loop runs until the condition becomes False

Syntax

initialization

while condition:
    statements
    increment/decrement

Explanation of Syntax

Example 1

i = 1

while i <= 3:
    print("Hi")
    i += 1

Output

Hi
Hi
Hi

Example 2

num = 1
sum = 0

while num <= 5:
    sum += num
    num += 1

print(sum)

Output

15

Explanation of Example

• Loop runs from 1 to 5
• Adds values → 1+2+3+4+5 = 15

How While Loop Works

Step 1

Python first checks the condition.

Step 2

If the condition is True:

• the loop block executes

Step 3

The variable is updated using increment or decrement.

Step 4

Python again checks the condition.

The process repeats until the condition becomes False.

Why while loop is Important

While loops are important because they help programs:

• repeat tasks automatically
• handle unknown repetitions
• create interactive systems
• process real-time conditions
• build dynamic applications

Difference Between for Loop and while Loop

Common Beginner Mistakes 

➤ Summary

• The while loop in Python is used to repeat a block of code as long as a condition remains True.

  Important concepts include:

  • initialization
  • condition checking
  • increment/decrement
  • infinite loops