Python break
Summary: in this tutorial, you’ll learn about the Python break statement and how to use it to exit a loop prematurely.
Introduction to the Python break statement
Sometimes, you wan to terminate a for loop or a while loop prematurely regardless of the results of the conditional tests. In these cases, you can use the break statement:
breakCode language: Python (python)
Typically, you use the break statement with the if statement to terminate a loop when a condition is True.
Using Python break with for loop
The following shows how to use the break statement inside a for loop:
for index in range(n):
# more code here
if condition:
breakCode language: Python (python)
In this syntax, if the condition evaluates to True, the break statement terminates the loop immediately. It won’t execute the remaining iterations.
This example shows how to use the break statement inside a for loop:
for index in range(0, 10):
print(index)
if index == 3:
breakCode language: Python (python)
Output:
0
1
2
3Code language: Python (python)
How it works.
- The
forloop iterates over 10 numbers from 0 to 9 and displays each of them on the screen. - However, when the loop counter is 3, the
breakstatement terminates the loop immediately. Therefore, the program shows only 4 numbers, from 0 to 3 to the screen.
When you use the break statement in a nested loop, it’ll terminate the innermost loop. For example:
for x in range(5):
for y in range(5):
# terminate the innermost loop
if y > 1:
break
# show coordinates on the screen
print(f"({x},{y})")Code language: Python (python)
Output:
(0,0)
(0,1)
(1,0)
(1,1)
(2,0)
(2,1)
(3,0)
(3,1)
(4,0)
(4,1)Code language: Python (python)
This example uses two for loops to show the coordinates from (0,0) to (5,5) on the screen.
The break statement in the nested loop terminates the innermost loop when the y is greater than one.
Therefore, you only see the coordiates whose y values are zero and one.
Using Python break statement with a while loop
The following shows how to use the break statement inside the while loop:
while condition:
# more code
if condition:
breakCode language: Python (python)
The following example uses the break statement inside a while loop.
It’ll prompt you for entering your favorite color. The program will stop once you enter quit:
print('-- Help: type quit to exit --')
while True:
color = input('Enter your favorite color:')
if color.lower() == 'quit':
breakCode language: Python (python)
Output:
-- Help: type quit to exit --
Enter your favorite color:red
Enter your favorite color:green
Enter your favorite color:blue
Enter your favorite color:quitCode language: Python (python)
How it works.
- The
while Truecreates an indefinite loop. - Once you enter
quit, the conditioncolor.lower() == 'quit'evaluates True that executes the break statement to terminate the loop. - The
color.lower()returns thecolorin lowercase so that you can enterQuit,QUITorquitto exit the program.
Summary
- Use the Python
breakstatement to terminate a for loop or a while loop prematurely.