From:	Erik Max Francis <max AT alcyone DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: domain of isspace()?
Date:	Tue, 06 May 1997 23:09:48 -0700
Organization:	Alcyone Systems
Lines:	21
Message-ID:	<33701CAC.7DE8FB9E@alcyone.com>
References:	<33711D51 DOT 430E AT geocities DOT com> <336FBFF9 DOT 63AF AT cs DOT com>
NNTP-Posting-Host:	newton.alcyone.com
Mime-Version:	1.0
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

John M. Aldrich wrote:

> In DJGPP, the ctype functions evaluate to a lookup of an array of
> flags.  You are perfectly safe to call them with any valid char value.

Right.  I should point out that the ctype.h is... functions take an int,
but the ANSI C standard (7.3, Character handling <ctype.h>) states that
it's only valid to call them with an unsigned char value or EOF.

So if you call isspace(-2) or isspace(23523), you're likely to have a
problem -- this is because, as you say, the ctype functions are
implemented as a lookup table, and looking up something other than -1 ..
255 would be a bad thing.

-- 
       Erik Max Francis, &tSftDotIotE / email / max AT alcyone DOT com
                     Alcyone Systems /   web / http://www.alcyone.com/max/
San Jose, California, United States /  icbm / 37 20 07 N  121 53 38 W
                                   \
                      "The future / is right there."
                                 / Bill Moyers

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