How To Use Break, Continue, and Pass Statements when Working with Loops in Python 3
Using for loops and while loops in Python allow you to automate and repeat tasks in an efficient manner.
But sometimes, an external factor may influence the way your program runs. When this occurs, you may want your program to exit a loop completely, skip part of a loop before continuing, or ignore that external factor. You can do these actions with
In Python, the
break statement provides you with the opportunity to exit out of a loop when an external condition is triggered. You’ll put the
break statement within the block of code under your loop statement, usually after a conditional
Let’s look at an example that uses the
break statement in a
number = 0 for number in range(10): number = number + 1 if number == 5: break # break here print('Number is ' + str(number)) print('Out of loop')
In this small program, the variable
number is initialized at 0. Then a
for statement constructs the loop as long as the variable
number is less than 10.
for loop, the number increases incrementally by 1 with each pass because of the line
number = number + 1.
Then, there is an
if statement that presents the condition that if the variable
number is equivalent to the integer 5, then the loop will break.
Within the loop is also a
print() statement that will execute with each iteration of the
for loop until the loop breaks, since it is after the
To see when we are out of the loop, we have included a final
print() statement outside of the
When we run this code, our output will be the following:
OutputNumber is 1 Number is 2 Number is 3 Number is 4 Out of loop
This shows that once the integer
number is evaluated as equivalent to 5, the loop breaks, as the program is told to do so with the
break statement causes a program to break out of a loop.
continue statement gives you the option to skip over the part of a loop where an external condition is triggered, but to go on to complete the rest of the loop. That is, the current iteration of the loop will be disrupted, but the program will return to the top of the loop.
continue statement will be within the block of code under the loop statement, usually after a conditional
Using the same
for loop program as in the Break Statement section above, we’ll use a
continue statement rather than a
number = 0 for number in range(10): number = number + 1 if number == 5: continue # continue here print('Number is ' + str(number)) print('Out of loop')
The difference in using the
continue statement rather than a
break statement is that our code will continue despite the disruption when the variable
number is evaluated as equivalent to 5. Let’s look at our output:
OutputNumber is 1 Number is 2 Number is 3 Number is 4 Number is 6 Number is 7 Number is 8 Number is 9 Number is 10 Out of loop
Here we see that the line
Number is 5 never occurs in the output, but the loop continues after that point to print lines for the numbers 6-10 before leaving the loop.
You can use the
continue statement to avoid deeply nested conditional code, or to optimize a loop by eliminating frequently occurring cases that you would like to reject.
continue statement causes a program to skip certain factors that come up within a loop, but then continue through the rest of the loop.
When an external condition is triggered, the
pass statement allows you to handle the condition without the loop being impacted in any way; all of the code will continue to be read unless a
break or other statement occurs.
As with the other statements, the
pass statement will be within the block of code under the loop statement, typically after a conditional
Using the same code block as above, let’s replace the
continue statement with a
number = 0 for number in range(10): number = number + 1 if number == 5: pass # pass here print('Number is ' + str(number)) print('Out of loop')
pass statement occurring after the
if conditional statement is telling the program to continue to run the loop and ignore the fact that the variable
number evaluates as equivalent to 5 during one of its iterations.
We’ll run the program and take a look at the output:
OutputNumber is 1 Number is 2 Number is 3 Number is 4 Number is 5 Number is 6 Number is 7 Number is 8 Number is 9 Number is 10 Out of loop
By using the
pass statement in this program, we notice that the program runs exactly as it would if there were no conditional statement in the program. The
pass statement tells the program to disregard that condition and continue to run the program as usual.
pass statement can create minimal classes, or act as a placeholder when working on new code and thinking on an algorithmic level before hammering out details.
pass statements in Python will allow you to use
for loops and
while loops more effectively in your code.
You can see
pass statements in action in our tutorial “How To Create a Twitterbot with Python 3 and the Tweepy Library.”