Real Python: How to Exit Loops Early With the Python Break Keyword

In Python, the break statement lets you exit a loop prematurely, transferring control to the code that follows the loop. This tutorial guides you through using break in both for and while loops. You’ll also briefly explore the continue keyword, which complements break by skipping the current loop iteration.

By the end of this tutorial, you’ll understand that:

• A break in Python is a keyword that lets you exit a loop immediately, stopping further iterations.
• Using break outside of loops doesn’t make sense because it’s specifically designed to exit loops early.
• The break doesn’t exit all loops, only the innermost loop that contains it.

To explore the use of break in Python, you’ll determine if a student needs tutoring based on the number of failed test scores. Then, you’ll print out a given number of test scores and calculate how many students failed at least one test.

You’ll also take a brief detour from this main scenario to examine how you can use break statements to accept and process user input, using a number-guessing game.

Take the Quiz: Test your knowledge with our interactive “How to Exit Loops Early With the Python Break Keyword” quiz. You’ll receive a score upon completion to help you track your learning progress:

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Interactive Quiz

How to Exit Loops Early With the Python Break Keyword

In this quiz, you'll test your understanding of the Python break statement. This keyword allows you to exit a loop prematurely, transferring control to the code that follows the loop.

Introducing the break Statement

Before proceeding to the main examples, here’s a basic explanation of what the break statement is and what it does. It’s a Python keyword that, when used in a loop, immediately exits the loop and transfers control to the code that would normally run after the loop’s standard conclusion.

You can see the basics of the break statement in a simple example. The following code demonstrates a loop that prints numbers within a range until the next number is greater than 5:

>>> fornumberinrange(10):... ifnumber>5:... break... print(number)... 012345

This short code example consists of a for loop that iterates through a range of numbers from 0 to 9. It prints out each number, but when the next number is greater than 5, a break statement terminates the loop early. So, this code will print the numbers from 0 to 5, and then the loop will end.

As break statements end loops early, it wouldn’t make sense for you to use them in any context that doesn’t involve a loop. In fact, Python will raise a SyntaxError if you try to use a break statement outside of a loop.

A key benefit of using break statements is that you can prevent unnecessary loop iterations by exiting early when appropriate. You’ll see this in action in the next section.

Breaking Out of a Loop With a Set Number of Iterations

Imagine you’re a teacher who evaluates the scores of your students. Based on the scores, you want to determine how many tests each student has failed. The following example demonstrates how you might accomplish this task using a for loop to iterate through the students’ test scores:

>>> scores=[90,30,50,70,85,35]>>> num_failed_scores=0>>> failed_score=60>>> forscoreinscores:... ifscore<failed_score:... num_failed_scores+=1...>>> print(f"Number of failed tests: {num_failed_scores}")Number of failed tests: 3