Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!yale!cmcl2!adm!smoke!gwyn
From: gwyn@smoke.brl.mil (Doug Gwyn)
Newsgroups: comp.lang.c
Subject: Re: Is it only ANSI C that allow #if to compare symbols?
Keywords: sun C #if
Message-ID: <14916@smoke.brl.mil>
Date: 21 Jan 91 21:12:50 GMT
References: <1991Jan18.170921.4866@resam.dk> <14900@smoke.brl.mil> <1991Jan21.090551.12909@resam.dk>
Organization: U.S. Army Ballistic Research Laboratory, APG, MD.
Lines: 16

In article <1991Jan21.090551.12909@resam.dk> andrew@resam.dk (Leif Andrew Rump) writes:
-The (Danish version of the) Ansi K&R compiler gives the following example:
[I assume you mean that some manual for some compiler gives the example.]
-#define	SYSTEM	SPARC
-#if	SYSTEM == SPARC
-  ...
-#else
-  ...
-#endif
-I was not able to find the book this morning but i _don't_ remember any
-defines giving the symbol SPARC any numerical value.

If not, then the example is incorrect.
(Well, actually it would work due to the expression being evaluated as 0==0,
but SYSTEM cannot be used to select among different system types in this way
unless each system-type macro is given a distinct value.)