What is the use of "else" after "for" loop in Python?

Question

It seems both of the below codes are printing the same, then what is the need of “else” block after “for” loop in python.

Code 1:

for i in range(10):
    print i
else:
    print "after for loop"

Code 2:

for i in range(10):
    print i

print "after for loop"

Thanks in advance.

Asked By: Rajesh Kumar

||

Source

Answer 1

else executes after for providing for wasn’t terminated with break:

for i in range(10):
    print i
    if i == 8:
        break # termination, no else    
else:
    print "after for loop"

Answered By: Dmitry Bychenko

Answer 2

From the documentation:

Loop statements may have an else clause; it is executed when the loop terminates through exhaustion of the list (with for) or when the condition becomes false (with while), but not when the loop is terminated by a break statement.

Follow the link for an example how this can be used.

Answered By: Aaron Digulla

Answer 3

This was originally enacted in order to get rid of all the "GOTO" statements in procedures without using flags:
It means "NO BREAK"

for i, value in enumerate(sequence):
    if value == target:
        break
else:           #<-- if we finish the loop and did not encounter break, return -1
    return -1
return 1        #<-- if we did encounter break, return 1

You can watch Raymond Hettinger’s Pycon talk that mentions the for/else construct here: Transforming Code into Beautiful, Idiomatic Python

Answered By: Reblochon Masque

What is the use of "else" after "for" loop in Python?

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