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Path: utzoo!mnetor!seismo!husc6!ddl
From: ddl@husc6.UUCP (Dan Lanciani)
Newsgroups: comp.lang.c,comp.sys.ibm.pc
Subject: Re: MS-DOS NRO (an 'NROFF'- 'RNO'-like Source in C)
Message-ID: <2065@husc6.UUCP>
Date: Sat, 23-May-87 19:44:30 EDT
Article-I.D.: husc6.2065
Posted: Sat May 23 19:44:30 1987
Date-Received: Sun, 24-May-87 01:32:35 EDT
References: <405@ritcv.UUCP> <725@thumper.UUCP> <345@polyslo.UUCP>
Distribution: na
Organization: Harvard University Computer Services
Lines: 24
Keywords: NRO
Xref: mnetor comp.lang.c:2230 comp.sys.ibm.pc:4320

In article <345@polyslo.UUCP>, mpatnode@polyslo.UUCP (Mike Patnode) writes:
> 	But... there is one more small problem for all you MSC an BSD
> 	4.2 users.  Look for two occurances of the following.
> 		toupper(p++)
> 	This is a BIG NO-NO since toupper is actually a macro which
> 	evaluates it's arguments 3 times!!!!!  In both cases simply add
> 	another line with just p++;

	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.  Therefore, toupper('A') will return garbage.  The correct
way to use toupper is something like:

if(islower(x))
	x = toupper(x);

	Note that Turbo C, some versions of Lattice, and whatever was
originally used to compile NRO define toupper and tolower as functions
which do the "right thing" while still eveluating only once (obviously).

					Dan Lanciani
					ddl@harvard.*