From: Al Viro <viro@ftp.linux.org.uk>
To: Satyam Sharma <satyam.sharma@gmail.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: double exclamation (!!) suckage in the kernel
Date: Fri, 25 May 2007 22:32:13 +0100 [thread overview]
Message-ID: <20070525213213.GM4095@ftp.linux.org.uk> (raw)
In-Reply-To: <a781481a0705251356s2e9e0e2dsbed40a84231cd4fa@mail.gmail.com>
On Sat, May 26, 2007 at 02:26:11AM +0530, Satyam Sharma wrote:
> also be brave enough to take a C quiz here :-)
>
> > what type should x have for !!x to be a valid expression?
>
> Any integer type (includes pointers)
Er, no... Pointers are not integer types *and* you can use ! on any
scalar type (including floating ones, even though it's not particulary
useful there).
> > what will be the type of result?
>
> int (I guess boolean for C99?)
Actually, ! and comparisons still give int in C99 (and !x is defined as
(x == 0) in all situations).
next prev parent reply other threads:[~2007-05-25 21:32 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-25 20:23 double exclamation (!!) suckage in the kernel Satyam Sharma
2007-05-25 20:28 ` Russell King
2007-05-25 20:32 ` Satyam Sharma
2007-05-25 20:37 ` Björn Steinbrink
2007-05-25 20:41 ` Al Viro
2007-05-25 20:56 ` Satyam Sharma
2007-05-25 21:03 ` Satyam Sharma
2007-05-25 21:32 ` Al Viro [this message]
2007-05-25 21:36 ` Al Viro
2007-05-25 21:37 ` Satyam Sharma
2007-05-25 21:14 ` David Miller
2007-05-26 13:41 ` Jan Engelhardt
[not found] <8oOAk-4mP-3@gated-at.bofh.it>
[not found] ` <8oPmF-5Fb-21@gated-at.bofh.it>
[not found] ` <8p4OH-3N0-15@gated-at.bofh.it>
2007-05-26 16:38 ` Bodo Eggert
2007-05-26 16:50 ` Al Viro
2007-05-29 8:26 ` Bodo Eggert
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