Path: utzoo!attcan!uunet!virtech!cpcahil
From: cpcahil@virtech.uucp (Conor P. Cahill)
Newsgroups: comp.lang.c
Subject: Re: compare strings, strcmp
Keywords: strcmp,strings
Message-ID: <1989Nov21.003145.27917@virtech.uucp>
Date: 21 Nov 89 00:31:45 GMT
References: <4463@blake.acs.washington.edu> <11605@smoke.BRL.MIL> <308@charyb.COM> <5139@mnetor.UUCP>
Organization: Virtual Technologies Inc.
Lines: 21

In article <5139@mnetor.UUCP>, lazer@mnetor.UUCP (Lazer Danzinger) writes:

> +This macro is "unsafe" because the macro arguments a and b are used twice,
> +hence possible side effect difficulties...

>     I see no possibility of side effects. What is unsafe is the
>     referencing of the location where a and b point to, without
>     first checking that they are not null pointers. 

wrongo.  you (the programmer) must do that before calling StrEqu.  This macro
was designed to be a replacement for using strcmp directly and therefore has
the same requirements as the strcmp function itself.  Calling
strcmp with a null pointer will result in a core dump on lots of machines
and undefined behavior on all others.

The side effects have been addressed in lots of other posts in this thread.
-- 
+-----------------------------------------------------------------------+
| Conor P. Cahill     uunet!virtech!cpcahil      	703-430-9247	!
| Virtual Technologies Inc.,    P. O. Box 876,   Sterling, VA 22170     |
+-----------------------------------------------------------------------+