Path: utzoo!utgpu!attcan!uunet!lll-winken!arisia!quintus!ok
From: ok@quintus.uucp (Richard A. O'Keefe)
Newsgroups: comp.lang.c
Subject: Re: Programming and international chara
Message-ID: <644@quintus.UUCP>
Date: 8 Nov 88 02:30:45 GMT
References: <532@krafla.rhi.hi.is> <44200016@uicsrd.csrd.uiuc.edu>
Sender: news@quintus.UUCP
Reply-To: ok@quintus.UUCP (Richard A. O'Keefe)
Organization: Quintus Computer Systems, Inc.
Lines: 14

In article <44200016@uicsrd.csrd.uiuc.edu> mcdaniel@uicsrd.csrd.uiuc.edu writes:
>One possible
>macro implementation is:
>	#define iscntrl(c)	( (c) >= 0 && (c) <= 037 )
>
>(The first test is because implementations are permitted by dpANS to
>have signed characters.)  In this case, if "c" has side effects, the
>side effects will be performed twice.

A reasonably well-known hack, where L and U are constant integer expressions,
is	#define inrange(x,L,U) ((unsigned)((x)-(L)) <= (unsigned)((U)-(L)))
It has the virtue that x is evaluated only once.  In this case:
	*define iscntrl(c) ((unsigned)(c) < 32)
I say "*define" because the usual definition of iscntrl() for ASCII
includes DEL as one of the cntrl characters.