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From: gwyn@smoke.BRL.MIL (Doug Gwyn)
Newsgroups: comp.std.c
Subject: Re: What is a constant expression
Message-ID: <11339@smoke.BRL.MIL>
Date: 19 Oct 89 10:18:28 GMT
References: <1219@crdos1.crd.ge.COM>
Reply-To: gwyn@brl.arpa (Doug Gwyn)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 19

In article <1219@crdos1.crd.ge.COM> davidsen@crdos1.UUCP (bill davidsen) writes:
>	#define CNTL(c) ('c' & 037)

>  What am I missing in the standard? In looking up initializers in the
>index, section 3.5.7 (L14) uses the term "constant expression." However
>the index doesn't seem to list that term.

Sure it does:
	constant expressions, 3.4

>  Don't waste your time telling me that's a bad way to do the macro, I
>didn't write it, and I don't defend it.

My recommendation for this abuse of the preprocessor, widely encountered
in code from Berkeley UNIX systems, is to change the macro to
	#define CNTRL(c) ((c) & 037)
then globally edit the source code to wrap the arguments with '',
e.g. in "ed":
	g/CTRL(/s/CTRL(\(.\))/CNTRL('\1')/g