[Tut] How to Stop a For Loop in Python

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How to Stop a For Loop in Python

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Python provides three ways to stop a for loop:

1. The for loop ends naturally when all elements have been iterated over. After that, Python proceeds with the first statement after the loop construct.
   
   
2. The keyword
   Code:

   break
   terminates a loop immediately. The program proceeds with the first statement after the loop construct.
   
   
3. The keyword
   Code:

   continue
   terminates only the current loop iteration, but not the whole loop. The program proceeds with the first statement in the loop body.
   

You can see each of these three methods to terminate a for loop in the following graphic:



Let’s dive into each of those three approaches next!

Method 1: Visit All Elements in Iterator

The most natural way to end a Python

Code:

for

loop is to deplete the iterator defined in the loop expression

Code:

for <var> in <iterator>

. If the iterator’s

Code:

next()

method doesn’t return a value anymore, the program proceeds with the next statement after the loop construct. This immediately ends the loop.

Here’s an example that shows how the for loop ends as soon as all elements have been visited in the iterator returned by the

Code:

range()

function:

Code:

s = 'hello world' for c in range(5): print(c, end='') # hello

Recommended Tutorial: Iterators, Iterables, and Itertools

Method 2: Keyword “break”

If the program executes a statement with the keyword

Code:

break

, the loop terminates immediately. No other statement in the loop body is executed and the program proceeds with the first statement after the loop construct. In most cases, you’d use the keyword

Code:

break

in an if construct to decide dynamically whether a loop should end, or not.

In the following example, we create a string with 11 characters and enter a for loop that ends prematurely after five iterations — using the keyword

Code:

break

in an

Code:

if

condition to accomplish that:

Code:

s = 'hello world' for i in range(10): print(s[i], end='') if i == 5: break # hello

As soon as the

Code:

if

condition evaluates to

Code:

False

, the

Code:

break

statement is executed—the loop ends.

Recommended Tutorial: How to End a While Loop?

Method 3: Keyword “continue”

The keyword

Code:

continue

terminates only the current loop iteration, but not the whole loop. The program proceeds with the first statement in the loop body. The most common use of continue is to avoid the execution of certain parts of the loop body, constrained by a condition checked in an if construct.

Here’s an example:

Code:

for i in range(10): if i == 5: break else: continue print('NEVER EXECUTED')

Python iterates over an iterator with 10 elements. However, in each iteration, it either ends the loop using

Code:

break

or continues with the next iteration using

Code:

continue

.

However, the remaining loop body that actually does something such as printing

Code:

'NEVER EXECUTED'

is, well, never executed.

Python Keywords Cheat Sheet

You can learn about the most important Python keywords in this concise cheat sheet—if you’re like me, you love cheat sheets as well!



You can download it here:

Summary

You’ve learned three ways to terminate a while loop.

• Method 1: The for loop terminates automatically after all elements have been visited. You can modify the iterator using the
  Code:

  __next__()
  dunder method.
  
  
• Method 2: The keyword
  Code:

  break
  terminates a loop immediately. The program proceeds with the first statement after the loop construct.
  
  
• Method 3: The keyword
  Code:

  continue
  terminates only the current loop iteration, but not the whole loop. The program proceeds with the first statement in the loop body.
  

Thanks for reading this tutorial—if you want to boost your Python skills further, I’d recommend you check out my free email academy and download the free Python lessons and cheat sheets here:

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Programmer Humor

Code:

Question: How did the programmer die in the shower? ☠

❗ Answer: They read the shampoo bottle instructions:
Lather. Rinse. Repeat.