Path: utzoo!attcan!uunet!ncrlnk!ncrcae!hubcap!gatech!uflorida!haven!adm!smoke!gwyn
From: gwyn@smoke.BRL.MIL (Doug Gwyn )
Newsgroups: comp.lang.c
Subject: Re: Programming and international chara
Message-ID: <8829@smoke.BRL.MIL>
Date: 9 Nov 88 10:37:37 GMT
References: <532@krafla.rhi.hi.is> <44200016@uicsrd.csrd.uiuc.edu>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 14

In article <44200016@uicsrd.csrd.uiuc.edu> mcdaniel@uicsrd.csrd.uiuc.edu writes:
>	#define iscntrl(c)	( (c) >= 0 && (c) <= 037 )

This is an invalid implementation.  The is*() functions may be implemented
as macros only if they are "safe" macros (i.e. evaluate the argument only
once).  Also, for valid arguments (ints in the range 0..CHAR_MAX and EOF)
the only negative argument that must be handled is EOF.

>                . . . Isascii and toascii are defined on all
>     integer values; the rest are defined only where isascii is
>     true and on the single non-ASCII value EOF (see stdio(3S)).

Because ANSI C does not have an isascii() function, the is*() tests
are required to work right for all character values.