From: Erik Max Francis 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 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit To: djgpp AT delorie DOT com DJ-Gateway: from newsgroup comp.os.msdos.djgpp Precedence: bulk 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 ) 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