Path: utzoo!attcan!uunet!charyb!will
From: will@kfw.COM (Will Crowder)
Newsgroups: comp.lang.c
Subject: Re: Determining machine characteristics (was: IsUnsigned() function?)
Message-ID: <1990Jul27.162611.14828@kfw.COM>
Date: 27 Jul 90 16:26:11 GMT
References: <1990Jul16.214155.5087@Neon.Stanford.EDU> <2936@mtung.ATT.COM> <17148@haddock.ima.isc.com> <3473@goanna.cs.rmit.oz.au>
Reply-To: will@kfw.com (Will Crowder)
Organization: KFW Corporation, Newbury Park, CA
Lines: 15

In article <3473@goanna.cs.rmit.oz.au> ok@goanna.cs.rmit.oz.au (Richard A. O'Keefe) writes:

>It's clear that an arithmetic expression which appears in _code_ must be
>evaluated as if evaluated by the target machine, but need arithmetic
>expressions in #ifs be evaluated the same way?  Is it possible for
>	#if is_ones_complement()
>to succeed and
>	if (is_ones_complement())
>to fail?

Yes, it is quite possible for that to fail.  The C preprocessor knows 
nothing about the C language itself.  For instance, try using a cast
in a preprocessor #if.

Will