python: behaviors of iterator.next() when a container changes

Asked May 07 '14 at 14:20

Active May 07 '14 at 14:57

Viewed 47 times

    >>> a
    [1, 2, 3]
    >>> it = iter(a)
    >>> it.next()
    1
    >>> a.remove(1)
    >>> a
    [2, 3]
    >>> it.next()
    3
    >>>

in the above codes, why the second it.next() returns 3 but not 2?

note: this question is totally different from this question, which involves the StopIteration while the problem here is in the middle.

edited May 23 '17 at 11:57

Community

asked May 07 '14 at 14:20

lily

1

Because the iterator object remembers the last position. – thefourtheye May 07 '14 at 14:21
@thefourtheye if itertator remembers the last position, it should be `2`, isn't it? – lily May 07 '14 at 14:24
1

Also see [Loop "Forgets" to Remove Some Items](http://stackoverflow.com/q/17299581); same principle applies. – Martijn Pieters May 07 '14 at 14:25
@devnull no, it is a different question. I have read the answer and it doesn't give me any hints – lily May 07 '14 at 14:28
@thefourtheye it is `2`, not `s` – lily May 07 '14 at 14:46
@thefourtheye it is not a duplicate, I have read that question, it is not the same as mine! – lily May 07 '14 at 14:47
@dm03514 it is not a duplicate, I have read that question, it is not the same as mine – lily May 07 '14 at 14:58

0 Answers0