0 == False but [] != False? - comp.lang.python

Message from discussion 0 == False but [] != False?

Erik Max Francis

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More options May 24 2007, 3:14 pm

Newsgroups: comp.lang.python

From: Erik Max Francis <m...@alcyone.com>

Date: Wed, 23 May 2007 22:14:13 -0700

Local: Thurs, May 24 2007 3:14 pm

Subject: Re: 0 == False but [] != False?

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Rajarshi wrote:
> This is a slightly naive question, but I know that 0 can be used to
> represent False. So

>>>> 0 == False
> True

> But, I know I can use [] to represent False as in

>>>> if not []: print 'empty'
> ...
> empty

> But then doing the following gives a surprising (to me!) result

>>>> [] == False
> False

> Could anybody point out why this is the case?

Because "representing False" (i.e., being false) and "being the same as
False" are not the same thing.

if x:
...

is not the same thing as

if x == True:
...

it's the same as

if bool(x):
...

So a more meaningful comparison of your two tests are:

>>> bool(0) == bool(False)
True
>>> bool([]) == bool(False)
True

--
Erik Max Francis && m...@alcyone.com && http://www.alcyone.com/max/
San Jose, CA, USA && 37 20 N 121 53 W && AIM, Y!M erikmaxfrancis
Woman was God's _second_ mistake.
-- Friedrich Nietzsche

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