Path: utzoo!utgpu!watmath!att!dptg!rutgers!gatech!ncar!ico!ism780c!haddock!karl
From: karl@haddock.ima.isc.com (Karl Heuer)
Newsgroups: comp.lang.c
Subject: Re: Atomic #defines (was Re: Password checking program)
Message-ID: <14480@haddock.ima.isc.com>
Date: 31 Aug 89 00:30:19 GMT
References: <15257@duke.cs.duke.edu> <652@lakart.UUCP> <10765@smoke.BRL.MIL> <1625@mcgill-vision.UUCP> <13899@bloom-beacon.MIT.EDU>
Reply-To: karl@haddock.ima.isc.com (Karl Heuer)
Organization: Interactive Systems, Cambridge, MA 02138-5302
Lines: 16

In article <13899@bloom-beacon.MIT.EDU> scs@adam.pika.mit.edu (Steve Summit) writes:
>I didn't want to require that <stdio.h> be #included before the header file
>that was trying to #define ERROR.  (I can't yet depend on ANSI's guarantee
>that multiple #inclusions of standard header files are safe, so I didn't have
>the header file in question #include <stdio.h> itself.  It occurs to me that
>	#ifndef EOF
>	#include <stdio.h>
>	#endif
>is probably a safe way to protect against a non-idempotent <stdio.h>...)

It works correctly if the user has already done the #include, or if they omit
it entirely, but not if they do it *after* #include'g your header.  The user
needs to be warned not to do that; you can't defend against it without having
write permission to stdio.h.

Karl W. Z. Heuer (ima!haddock!karl or karl@haddock.isc.com), The Walking Lint