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From: mouse@mcgill-vision.UUCP (der Mouse)
Newsgroups: comp.lang.c
Subject: Re: Distinguished pointers (was Re: Weird syscall returns)
Message-ID: <854@mcgill-vision.UUCP>
Date: Wed, 5-Aug-87 03:52:30 EDT
Article-I.D.: mcgill-v.854
Posted: Wed Aug  5 03:52:30 1987
Date-Received: Sat, 15-Aug-87 08:17:57 EDT
References: <1158@copper.TEK.COM> <8317@utzoo.UUCP>
Organization: McGill University, Montreal
Lines: 23

In article <8317@utzoo.UUCP>, henry@utzoo.UUCP (Henry Spencer) writes:
>> I think we need more distinguished pointer values [...].  I have
>> [need for other FILE * values]

> This is utterly trivial to do [in current C].  Put the following code
> fragment into a file and include it in your library:
> 	char myio_no;
> 	char myio_null;
> And then include this in the include file for your library:
> 	#define	NOFILE		((FILE *)&myio_no)
> 	#define	NULLFILE	((FILE *)&myio_null)
> This works just fine without any unportable messes like "(char *)-1".

Hm.  I see no guarantee that NOFILE != NULLFILE.  Do it right:

FILE myio_no;
FILE myio_null;
#define NOFILE (&myio_no)
#define NULLFILE (&myio_null)

					der Mouse

				(mouse@mcgill-vision.uucp)