Master Python’s while Loop: From Basics to Infinite Loops

Python while loop overview

In Python, the while statement repeatedly executes a block of code as long as a given condition evaluates to true. while 判断条件：执行语句…… The body can be a single statement or a block. The condition may be any expression; any non‑zero or non‑null value is considered true. When the condition becomes false, the loop terminates.

Execution flowchart:

Gif demonstration of Python while execution

Example

Output of the above code:

The loop also supports the continue statement to skip the current iteration and the break statement to exit the loop entirely. A constant true condition creates an infinite loop.

Infinite loop

If the condition is always true, the loop runs indefinitely. Example:

Output of the infinite loop example:

Note: You can interrupt an infinite loop with CTRL+C.

while…else clause

In Python, a while … else block executes the else part when the loop condition becomes false.

Output of the above example:

Simple statement group

If the loop body contains only one statement, it can be placed on the same line as the while statement.

Note: Infinite loops can be stopped with CTRL+C.