Equality operator

[italy]

Why doesn't this statement execute in Python:

1 == not 0

I get a syntax error, but I don't know why.

Thanks,
Adam Roan

[Kent Johnson]

Re: Equality operator

italy wrote:[color=blue]
> Why doesn't this statement execute in Python:
>
> 1 == not 0
>
> I get a syntax error, but I don't know why.[/color]

Because == has higher precedence than 'not', so you are asking for
(1 == not) 0

Try[color=blue][color=green][color=darkred]
>>> 1 == (not 0)[/color][/color][/color]
True

Kent
[color=blue]
>
> Thanks,
> Adam Roan
>[/color]

[Marek Kubica]

Re: Equality operator

[color=blue]
> Why doesn't this statement execute in Python:
>
> 1 == not 0
>
> I get a syntax error, but I don't know why.[/color]

This does: 1 == (not 0)
I presume Python treats it like

1 (== not) 0

Which is a SyntaxError

greets,
Marek

[Chris Grebeldinger]

Re: Equality operator

"not" has a lower priority than non-Boolean operators, so not a == b is
interpreted as not (a == b), and a == not b is a syntax error.

http://docs.python.org/lib/boolean.html

[Marc 'BlackJack' Rintsch]

Re: Equality operator

In <1110055534.040 063.304150@f14g 2000cwb.googleg roups.com>, italy wrote:
[color=blue]
> Why doesn't this statement execute in Python:
>
> 1 == not 0
>
> I get a syntax error, but I don't know why.[/color]

`==` has a higher precedence than `not` so Python interprets it as::

(1 == not) 0

This works::
[color=blue][color=green][color=darkred]
>>> 1 == (not 0)[/color][/color][/color]
True

Ciao,
Marc 'BlackJack' Rintsch

[Anthony Boyd]

Re: Equality operator


italy wrote:[color=blue]
> Why doesn't this statement execute in Python:
>
> 1 == not 0
>
> I get a syntax error, but I don't know why.
>
> Thanks,
> Adam Roan[/color]

Of course, you would normally want to use != to see if something is not
equal to something else.

1 != 0
True