Re: double exclamation (!!) suckage in the kernel

From: Satyam Sharma
Date: Fri May 25 2007 - 17:04:15 EST


On 5/26/07, Satyam Sharma <satyam.sharma@xxxxxxxxx> wrote:
On 5/26/07, Al Viro <viro@xxxxxxxxxxxxxxxx> wrote:
>
> That's a question for a quiz in introductory course on C:

Ugh ... ok, I've embarrassed myself publicly already, so I'll
also be brave enough to take a C quiz here :-)

Hmmm, and now I seem to have flunked ...

> what type should x have for !!x to be a valid expression?

Any integer type (includes pointers)

gcc doesn't seem to mind a ! on a float either (does it do an implicit
cast to int first?). Can't think of too many situations where one would
want to do a ! on a float, actually, in any case ...

> what will be the type of result?

int (I guess boolean for C99?)
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