Xref: news2.mv.net comp.os.msdos.djgpp:8456
From: Elliott Oti <e DOT oti AT stud DOT warande DOT ruu DOT nl>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Problem with #define's under DJGPP
Date: Mon, 09 Sep 1996 10:34:50 -0700
Organization: Academic Computer Centre Utrecht, (ACCU)
Lines: 73
Message-ID: <3234553A.6C@stud.warande.ruu.nl>
References: <511bnh$nne AT tornews DOT torolab DOT ibm DOT com>
NNTP-Posting-Host: warande1078.warande.ruu.nl
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
To: wallaker AT vnet DOT ibm DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

Aron Wallaker wrote:
> 
> I'm having a problem trying to use #define's in a header file to define
> constants for use in my C code. Here's an example:
> 
> --File:STAR.H---------------------
> 
> #define  STARPOPULATION    0x200
> 
> --FILE:STAR.C---------------------
> #include"star.h"
> 
> void main(void)
> {
>    int LocalStarPop = STARPOPULATION;  // This works.
> 
>    for(x=0;x < STARPOPULATION ; x++)   // This doesn't, see below.
>    {
>        //whatever
>    }
> }
> 
> When I try to set a local variable to the value I have #define'd in the
> header file, it seems to work fine. However, if I try to use the #define
> value in a function call, or a structure such as the for(... above, I
> get a "parsing error in line...." error. I checked the FAQ's I could find,
> and I saw no mention of this behavior. I have DJGPP V2.0 which I dl'd off
> simtel about 2 weeks back. Does this look familiar to anyone ? I use this
> type of #define all the time in Watcom, so I'd be pretty dissapointed if
> I couldn't do something similar under DJGPP. I tried searching for any
> command-line parameters which might affect the preprocessor and how it
> handles #define's but I didn't find any. I would appreciate any feedback
> anyone could give me.
> 
> Thanks,
> 

I tried compiling the fragment above and it compiled fine. I don't know 
if your code is literally equivalent to the fragment above, but you didn't
declare x first. The only thing I added was "int x;  " and "puts("*") "
in the inner loop. It worked perfectly.
I suspect the problem lies elsewhere in your code : in my experience
the warning "parsing error" usually means you forgot a "{" or ")" or
";" or ' " ' -- or have one too many. So check that you didn't declare 
     #define SHIT 0x34;   <--- watch that ";"
or
     #define PISS ((a)/(b)))   <---- one ")" too many.

Run lint or a braces-checker over your code; if you don't have lint
replace the #defines with global variables and recompile a sample.
If it works as expected then recheck the form of the #defines; if your
program crashes then you know you left a loose brace somewhere in your code.
The preprocessor in such cases doesn't stop where the mistake was made,
but where it got into trouble. For instance:

1    void  ShitFunction(void)
2     { puts("Oh shit!");      <--- oops, no closing brace

3     main()
4   { puts("Oh heck");
5     ShitFunction();
6    } 
     
doesn't give an error report at line 2 but at line 5 ("function ShitFunction already
declared") and line 6 ("Parsing error in line 6"), because it thinks lines 3-6
are part of the definition of ShitFunction and expects closing braces at line 6.
In this respect DJGPP's warnings are less helpfull than lint's would be.
Try compiling with -Wall enabled; it is also helpful.   

Happy debugging,
Elliott

PS C++ comment-style *IS* allowed in C programs with DJGPP V2. Feel free to use //.