Date: Thu, 5 Oct 1995 11:00:43 +0100 From: se@zpr.uni-koeln.de (Stefan Esser) To: Andrew White <awhite@dca.net> Cc: bugs@freebsd.org Subject: Re: bug with gcc 2.6.2? Message-ID: <199510051000.AA00067@Sysiphos> In-Reply-To: Andrew White <awhite@dca.net> "bug with gcc 2.6.2?" (Oct 5, 2:42)
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On Oct 5, 2:42, Andrew White wrote:
} Subject: bug with gcc 2.6.2?
} FreeBSD bugs list:
}
} The following code generates a segmentation violation using gcc 2.6.2 as
} shipped with FreeBSD 2.0-RELEASE. It shouldn't! It seems as if any of
} the string functions (strcmp, strcpy, etc) bomb when invoked with a null
} string.
This is not a compiler error, but intended behaviour ...
NULL is not a string, but a pointer to NO string.
FreeBSD on purpose makes address 0 unavailable, just to
catch such errors (as just about any other Unix system).
} I compiled this using gcc 2.3.3 under AIX 3.2.5, and it works as expected
} (prints "x is -1" when run). I am compiling this program (I called it
} test.c) with: "gcc -o test test.c"... am I missing something obvious??
} s=NULL;
}
} x=strcmp(s,"test");
Yes. The test result is undefined, and the system lets
you know. If you want to use a NULL pointer to imply an
empty string, then you better code this as:
x=strcmp(s ? s : "", "test");
assuming that the second parameter in fact is not a
constant string, but variable and known to not be
another NULL pointer ...
Regards, STefan
--
Stefan Esser, Zentrum fuer Paralleles Rechnen Tel: +49 221 4706021
Universitaet zu Koeln, Weyertal 80, 50931 Koeln FAX: +49 221 4705160
==============================================================================
http://www.zpr.uni-koeln.de/staff/esser/esser.html <se@ZPR.Uni-Koeln.DE>
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