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From: jae@ncoast.UUCP (Jeff Evans)
Newsgroups: comp.lang.c,comp.sys.ibm.pc
Subject: Re: MSC toupper (was  Re: MS-DOS NRO )
Message-ID: <2576@ncoast.UUCP>
Date: Sun, 31-May-87 16:37:42 EDT
Article-I.D.: ncoast.2576
Posted: Sun May 31 16:37:42 1987
Date-Received: Wed, 3-Jun-87 04:08:58 EDT
References: <405@ritcv.UUCP> <725@thumper.UUCP> <345@polyslo.UUCP> <348@polyslo.UUCP>
Distribution: na
Organization: Cleveland Public Access UN*X, Cleveland, OH
Lines: 37
Keywords: NRO
Summary: toupper is a function AND a macro ...
Xref: mnetor comp.lang.c:2299 comp.sys.ibm.pc:4510

In article <348@polyslo.UUCP>, mpatnode@polyslo.UUCP (Mike Patnode) writes:
> In article <2065@husc6.UUCP> ddl@husc6.UUCP (Dan Lanciani) writes:
> >In article <345@polyslo.UUCP>, mpatnode@polyslo.UUCP (Mike Patnode) writes:
> >> 		toupper(p++)
> >> 	This is a BIG NO-NO since toupper is actually a macro which
> >> 	evaluates it's arguments 3 times!!!!!
> >
> >	Not quite.  This is a no-no, but for a different reason.  The macros
> >toupper and tolower do not evaluate their arguments more than once.  (At
> >least on BSD and MSC 4.0 and other "compatible" systems.)  In order to
> >avoid multiple eveluation, these macros do NOT check that their arguments
> >are suitable.
> 	Well Dan this is straight out of my ctype.h:
> 
> #define toupper	((isupper(c)) ? _tolower(c) : (c))
> 
>       Upon closer evaluation I now see the argument is only evaluated 2
>       times.  But this was with MSC 3.00 so 4.0 may have change.

  Here it is, straight from the horses mouth ...
(Microsoft C 4.0 Runtime Lib. Manual p. 406  [for toascii - toupper])

 These functions are implemented as macros.  However, tolower and
toupper are also implemented as functions, because the macro versions
do not correctly handle arguments with side effects.  The function versions
can be used by removing the macro definitions through #undef directives
or by not including ctype.h.  Function declarations of tolower and
toupper are given in stdlib.h.

   I had the same problem using the macro version of toupper,  but the
problem disappeared with the function version.

-- 
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|      Jeff Evans      Bailey Controls Co. -  Systems Engineering           |
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  Disclaimer : My views are of my own creation ...  I had no help.