the continue in for else in python

Question

for ele in eles:
   for i in xrange(10):
       try:
            #do something
           break
        except:
            continue
   else:
       if some condition:
           continue
       #do something

consider above code, i know the break will break the inner for loop, the first continue will continue inner for loop, what about the second continue? which for loop will it continue?

Why not try an example and see? Think about this, though - is the inner `for` loop still running when the `else` block is reached? — jonrsharpe, Apr 20 '15 at 10:53
@musefan: the `else` is executed if the `for` loop completed without being interrupted. E.g. if no `break` statement was executed. Wonderfully useful when [calculating prime numbers](http://stackoverflow.com/a/568684) for example. — Martijn Pieters, Apr 20 '15 at 10:57
@MartijnPieters: Ahhh, that is quite interesting... though perhaps not the best choice of keyword using `else`. Also, that prime number example function, would you even need the `else`? Surely it would work just returning true, as it would only be hit if it didn't return false already — musefan, Apr 20 '15 at 10:59
@musefan: the poor choice of the `else` keyword has been cited a few days ago on the python-dev mailing list. :) — Andrea Corbellini, Apr 20 '15 at 11:01
@musefan: yes, the feature is wonderful, the exact word used not so much. — Martijn Pieters, Apr 20 '15 at 11:02
@jonrsharpe: [here you are](https://mail.python.org/pipermail/python-ideas/2015-April/032995.html): *in the second case, the for-loop, "else" is not the best choice of keyword* (it was actually posted on python-ideas, not python-dev). — Andrea Corbellini, Apr 20 '15 at 14:14

score 0 · Accepted Answer · answered Apr 20 '15 at 10:53

The latest continue takes effect on the outer for loop, as demonstrated by the following example:

>>> for x in [1, 2, 3]:
...     for y in [4, 5, 6]:
...         print('x =', x, 'y =', y)
...     else:
...         continue
...     print('here')
... 
x = 1 y = 4
x = 1 y = 5
x = 1 y = 6
x = 2 y = 4
x = 2 y = 5
x = 2 y = 6
x = 3 y = 4
x = 3 y = 5
x = 3 y = 6

Note that "here" gets never printed.

Also, note that the inner for loop cannot be continued in any way: the else block is executed when the iterator is exhausted (in my example: when all the ys in [4, 5, 6] have been printed) and when no break statements have been executed. Because the iterator has been exhausted, there are no ways to make it produce more values.

the continue in for else in python

1 Answers1