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From: diamond@jit533.swstokyo.dec.com (Norman Diamond)
Newsgroups: comp.sys.dec
Subject: Re: strcat(foo,NULL) core dumps on Ultrix
Keywords: dec c strcat
Message-ID: <1991Jun12.041230.12264@tkou02.enet.dec.com>
Date: 12 Jun 91 04:12:30 GMT
References: <966@sdrc.COM>
Sender: usenet@tkou02.enet.dec.com (USENET News System)
Reply-To: diamond@jit533.enet@tkou02.enet.dec.com (Norman Diamond)
Organization: Digital Equipment Corporation Japan , Tokyo
Lines: 30

In article <966@sdrc.COM> wggabb@sdrc.COM (Rob Gabbard) writes:
>A call to strcat with NULL as the second argument core dumps with a memory 
>fault on Ultrix.  Why would anyone want to do this anyway ? How about....
>	strcat(foo,getenv("FOO"))
>		instead of
>	if (getenv("FOO")) strcat(foo,getenv("FOO"));

The behavior is undefined according to the C standard.  Core dumps are
a common result (although they used to be less common when one particular
hardware architecture used to be more common).

If you want to change the C language (including the standard library), wait
for the ANSI committee to begin preparing the next revision of the language,
and make your suggestions to them.  It probably won't be a long wait;
proceedings for the 1989 standard began around 8 years ago.  They have
probably heard this one before, so you will probably have to get a lot
of people on your side to join the committee and vote for your proposal.

>Actually, just coding strcat(foo,NULL) will dump.  Anyone run into this ?

Yes.  Mostly new programmers, and also some irresponsible (i.e. experienced
enough to know better, but lazy -- they know who they are) ones.

>Am I doing a no-no here.

Yes.
--
Norman Diamond       diamond@tkov50.enet.dec.com
If this were the company's opinion, I wouldn't be allowed to post it.
Permission is granted to feel this signature, but not to look at it.