Strange behavior with sort()

Thu Feb 27 01:40:53 EST 2014

On Thu, Feb 27, 2014 at 07:24:24AM +0100, ast wrote:
> Hello
>> box is a list of 3 integer items
>> If I write:
>> box.sort()
> if box == [1, 2, 3]:
>>> the program works as expected. But if I write:
>> if box.sort() == [1, 2, 3]:
>> it doesn't work, the test always fails. Why ?
>> Thx
> -- 
> https://mail.python.org/mailman/listinfo/python-list

Because when you call the .sort() method on a list, it does the sort
in-place, instead of returning a sorted copy of the list. Check this:
>>> [2,1,3].sort()
>>>
The method does not return a value, that's why the direct comparison
fails.
What you might want is to use the sorted() method on the list, like
this:
>>> sorted([2,1,3])
[1, 2, 3]
>>> sorted([2,1,3]) == [1,2,3]
True
-- 
Eduardo Alan Bustamante López