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From: 702WFG%SCRVMSYS.BITNET@cornellc.cit.cornell.edu (bill gunshannon)
Newsgroups: comp.os.minix
Subject: Re: Where is isascii(c)?
Message-ID: <9936@nigel.udel.EDU>
Date: 2 Feb 90 17:33:19 GMT
Sender: mmdf@udel.EDU
Lines: 19

>From:         Christoph van Wuellen <HBO043%DJUKFA11.BITNET@CUNYVM.CUNY.EDU>
>
><ctype.h> indeed is very messy. There is much code around which, e.g.,
>does tolower(x) without checking in advance if x is an upper case letter.
>This is wrong on the machines I work on since the tolower macro just adds
>'a'-'A'. I don't know if some versions of tolower do the check, but this
>has lead to errors in the past.

A quick galnce at my SYS V  manual says: "The macro _tolower requires an
uppercase letter as its argument; its result is the corresponding lowercase
letter.  Arguments outside the domain cause undefined results."

I haven' read it specificly but I doubt that ANSI or POSIX have made any
substantial change to this philosophy.  I would say it is up to the
programmer to make sure he only passes it valid data.  After all, isn't
that why we have "isupper()"??  :-)

                                          bill gunshannon
                                       702WFG@SCRVMSYS.BITNET