"0 in [True,False]" returns True

Carsten Haese carsten at uniqsys.com
Mon Dec 12 22:38:31 CET 2005


On Mon, 2005-12-12 at 16:26, Pierre Quentel wrote:
> Hi all,
> 
> In some program I was testing if a variable was a boolean, with this 
> test : if v in [True,False]
> 
> My script didn't work in some cases and I eventually found that for v = 
> 0 the test returned True
> 
> So I changed my test for the obvious "if type(v) is bool", but I still 
> find it confusing that "0 in [True,False]" returns True
> 
> By the way, I searched in the documentation what "obj in list" meant and 
> couldn't find a precise definition (does it test for equality or 
> identity with one of the values in list ? equality, it seems) ; did I 
> miss something ?

Where/how did you search? http://docs.python.org/lib/typesseq.html
states unambiguously that "x in s" returns "True if an item of s is
equal to x, else False"

HTH,

Carsten.





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