Python Basics · Control Flow · Lesson 10 of 36

while Loops

Concept

while Loops

while loops repeat as long as a condition is true. Remember to update the condition or you will loop forever.

break exits a loop immediately, and continue skips to the next iteration — both work in while and for loops alike.

By the end of this lesson

Explain the core idea behind while Loops.
Predict output before running a change.
Test one realistic and one unusual input.
Use the result to make the next decision.

How to study this page

1. Read one concept.
2. Change the example.
3. Run, compare, and explain.
4. Complete the challenge below.

Syntax

while condition:
    # code

ExampleRunnable

count = 0
while count < 3:
    print("Count:", count)
    count += 1

Try it Yourself »

Self-check before continuing

Without looking at the example, describe what changes when you modify one input in while Loops. Then reopen the editor and prove your explanation with a small test.

You are ready to continue when you can predict, test, and explain the result.

Your turn

Write a while loop that counts down from 5 to 1.

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Console

Output will appear here...