Break and Continue: While Loops

BartC bc at freeuk.com
Thu Jun 23 11:52:11 EDT 2016


On 23/06/2016 12:39, Chris Angelico wrote:
> On Thu, Jun 23, 2016 at 8:15 PM, BartC <bc at freeuk.com> wrote:
>> Actually pretty much any expression can be used, because Python can
>> interpret almost anything as either True or False. Don't ask for the rules
>> because they can be complicated, but for example, zero is False, and any
>> other number is True. I think.
>
> The rules are very simple. Anything that represents "something" is
> true, and anything that represents "nothing" is false. An empty
> string, an empty list, an empty set, and the special "None" object
> (generally representing the absence of some other object) are all
> false. A string with something in it (eg "Hello"), a list with
> something in it (eg [1,2,4,8]), etc, etc, are all true.

Maybe I was thinking of 'is' where sometimes the results are unintuitive.

But even with ordinary conditionals, False is False, but [False] is 
True. And [] is False, while [[]] is True. A class instance is always 
True, even when empty. And then "False" is True as well!

-- 
Bartc



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