Why do integers compare equal to booleans?
duncan smith
duncan at invalid.invalid
Fri Nov 16 10:17:28 EST 2018
On 16/11/18 14:51, Steve Keller wrote:
> Why do the integers 0 and 1 compare equal to the boolean values False
> and True and all other integers to neither of them?
>
> $ python3
> Python 3.5.2 (default, Nov 12 2018, 13:43:14)
> [GCC 5.4.0 20160609] on linux
> Type "help", "copyright", "credits" or "license" for more information.
> >>> 0 == False
> True
> >>> 1 == True
> True
> >>> 2 == False
> False
> >>> 2 == True
> False
> >>> -1 == False
> False
> >>> -1 == True
> False
> >>>
>
> Since these are objects of different types I would expect they cannot
> be equal. I know that 0 means false and != 0 means true in C, C++,
> etc. but in Python that surprises me.
>
> Steve
>
>>> isinstance(False, int)
True
>>> isinstance(True, int)
True
>>> False.real
0
>>> True.real
1
>>>
At least in recent Pythons.
Duncan
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