The break and continue statement

The break statement is used to break out of a loop statement i.e. stop the execution of a looping statement, even if the loop condition has not become False or the sequence of items has not been completely iterated over.

An important note is that if you break out of a for or while loop, any corresponding loop else block is not executed.

Example:

#!/usr/bin/python
# Filename: break.py
 
while True:
    s = input('Enter something : ')
    if s == 'quit':
        break
    print('Length of the string is', len(s))
print('Done')

Output:

   $ python break.py
   Enter something : Programming is fun
   Length of the string is 18
   Enter something : When the work is done
   Length of the string is 21
   Enter something : if you wanna make your work also fun:
   Length of the string is 37
   Enter something :       use Python!
   Length of the string is 12
   Enter something : quit
   Done

How It Works:

In this program, we repeatedly take the user's input and print the length of each input each time. We are providing a special condition to stop the program by checking if the user input is 'quit'. We stop the program by breaking out of the loop and reach the end of the program.

The length of the input string can be found out using the built-in len function.

Remember that the break statement can be used with the for loop as well.

The continue Statement

The continue statement is used to tell Python to skip the rest of the statements in the current loop block and to continue to the next iteration of the loop.

Example:

#!/usr/bin/python
# Filename: continue.py
 
while True:
    s = input('Enter something : ')
    if s == 'quit':
        break
    if len(s) < 3:
        print('Too small')
        continue
    print('Input is of sufficient length')
    # Do other kinds of processing here...

Output:

   $ python continue.py
   Enter something : a
   Too small
   Enter something : 12
   Too small
   Enter something : abc
   Input is of sufficient length
   Enter something : quit

How It Works:

In this program, we accept input from the user, but we process the input string only if it is at least 3 characters long. So, we use the built-in len function to get the length and if the length is less than 3, we skip the rest of the statements in the block by using the continue statement. Otherwise, the rest of the statements in the loop are executed, doing any kind of processing we want to do here.

Note that the continue statement works with the for loop as well.

-Swaroopch