How to use while true in python

PythonHow-ToBeginner · 3 min read

How to Use while True Loop in Python: Simple Guide

In Python, while True creates an infinite loop that runs until you stop it manually or use a break statement inside the loop. This is useful for repeating actions until a condition inside the loop is met.

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Syntax

The while True loop runs endlessly because the condition True is always true. Inside the loop, you usually add a break statement to stop the loop when needed.

while True: starts the infinite loop
code block: the repeated actions inside the loop
break: stops the loop when a condition is met

python

while True:
    # repeated code here
    if some_condition:
        break

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Example

This example asks the user to enter a number repeatedly until they type 'exit'. It shows how while True keeps the program running and break stops it.

python

while True:
    user_input = input("Enter a number or 'exit' to stop: ")
    if user_input.lower() == 'exit':
        print("Loop stopped.")
        break
    print(f"You entered: {user_input}")

Output

Enter a number or 'exit' to stop: 5 You entered: 5 Enter a number or 'exit' to stop: 10 You entered: 10 Enter a number or 'exit' to stop: exit Loop stopped.

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Common Pitfalls

One common mistake is forgetting the break statement, which causes the loop to run forever and freeze the program. Another is placing break incorrectly so it never runs.

Always ensure your loop has a clear exit condition inside.

python

while True:
    print("This will print forever!")

# Correct way:
while True:
    answer = input("Type 'stop' to end: ")
    if answer == 'stop':
        break

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Quick Reference

Use while True for loops that need to run until a specific event happens inside the loop. Always pair it with break to avoid infinite loops.

while True: start infinite loop
break: exit loop
continue: skip to next loop cycle

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Key Takeaways

Use while True to create loops that run until you manually stop them.

Always include a break statement inside to avoid infinite loops.

Place the break where the exit condition is checked.

Infinite loops are useful for waiting on user input or events.

Test loops carefully to prevent freezing your program.