Path: utzoo!utgpu!jarvis.csri.toronto.edu!dgp.toronto.edu!flaps
Newsgroups: comp.lang.c
From: flaps@dgp.toronto.edu (Alan J Rosenthal)
Subject: Re: Assorted C Questions
Message-ID: <1989Sep3.232530.6354@jarvis.csri.toronto.edu>
References: <4294@udccvax1.acs.udel.EDU>
Date: 4 Sep 89 03:25:30 GMT

gdtltr@vax1.acs.udel.EDU (Gary D Duzan) writes:
>how necessary are #if directives?  It seems to me that it adds too much
>complexity to the preprocessor.

Indeed it does add a lot of complexity to the preprocessor.  I think that's why
most people no longer separate the preprocessor and the parser so much these
days.

I don't think expression handling in the preprocessor is SO important.  I
currently use a C implementation lacking it, and I don't really miss it much.
What I do miss is that I also can't say "#if THING" where THING is previously
#defined to be zero or non-zero.  Do put that in.

Of course, your implementation is not really C without expression handling in
the preprocessor.  You'll probably want to add it some day.

>Also, what exactly is a #pragma?  An example would help.

Examples:    #pragma listing
	     #pragma used-heavily(i, j, r)

If you just ignore all #pragma lines you'll be fine.  If you just abort at any
#pragma line, well, people differ on whether or not that's ok.

ajr