From: David Miller <davem@davemloft.net>
To: satyam.sharma@gmail.com
Cc: linux-kernel@vger.kernel.org
Subject: Re: double exclamation (!!) suckage in the kernel
Date: Fri, 25 May 2007 14:14:21 -0700 (PDT) [thread overview]
Message-ID: <20070525.141421.73699719.davem@davemloft.net> (raw)
In-Reply-To: <a781481a0705251323s6b5c8014t48e8d2ad63e8434a@mail.gmail.com>
From: "Satyam Sharma" <satyam.sharma@gmail.com>
Date: Sat, 26 May 2007 01:53:59 +0530
WHat is with multiple people asking about "!!" all of a
sudden today?
> Are all these occurrences merely the debris of
> s/something/!notsomething/g kind of patches or is there some
> dark, unknown C / gcc wizardry I have absolutely no clue of?
"!!" is used in contexts where pointers might be being
tested as well as plain integers, the "!!" turns a pointer
into the equivalent integer boolean for testing.
NULL pointers become 0
non-NULL pointers become 1
next prev parent reply other threads:[~2007-05-25 21:14 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
2007-05-25 21:36 ` Al Viro
2007-05-25 21:37 ` Satyam Sharma
2007-05-25 21:14 ` David Miller [this message]
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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