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From: "paolo dot bonzini at lu dot unisi dot ch" <sourceware-bugzilla@sources.redhat.com>
To: glibc-bugs-regex@sources.redhat.com
Subject: [Bug regex/1278] regex undefined behavior with shifting past word length
Date: Fri, 02 Sep 2005 06:17:00 -0000	[thread overview]
Message-ID: <20050902061715.27945.qmail@sourceware.org> (raw)
In-Reply-To: <20050831193645.1278.eggert@gnu.org>


------- Additional Comments From paolo dot bonzini at lu dot unisi dot ch  2005-09-02 06:17 -------
Subject: Re:  regex undefined behavior with shifting past
 word length


>For example, on a one's complement host, ~0 has the numeric value
>zero, i.e., ~0 == 0.  Also, ~0 is of type int.  When ~0 is converted
>to unsigned int, it is converted by value, not by bit-pattern.  (The C
>Standard requires this.)  Hence ((unsigned) ~0) is equivalent to
>((unsigned) 0), which in turn is equivalent to 0u, which is zero.
>  
>
So you want ~0u, but not -1.

Paolo


-- 


http://sources.redhat.com/bugzilla/show_bug.cgi?id=1278

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  parent reply	other threads:[~2005-09-02  6:17 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-08-31 19:37 [Bug regex/1278] New: " eggert at gnu dot org
2005-08-31 19:37 ` [Bug regex/1278] " eggert at gnu dot org
2005-09-01  7:04 ` paolo dot bonzini at lu dot unisi dot ch
2005-09-01 10:00 ` schwab at suse dot de
2005-09-01 22:29 ` eggert at gnu dot org
2005-09-02  6:17 ` paolo dot bonzini at lu dot unisi dot ch [this message]
2005-09-02 10:21 ` schwab at suse dot de
2005-09-02 23:17 ` eggert at gnu dot org
2005-09-06  7:32 ` eggert at gnu dot org
2005-09-06 23:30 ` drepper at redhat dot com

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