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From: edw@ius2.cs.cmu.edu.UUCP
Newsgroups: comp.lang.c
Subject: Re: "unix" macro on System V?
Message-ID: <1076@ius2.cs.cmu.edu>
Date: Sun, 29-Mar-87 01:00:21 EST
Article-I.D.: ius2.1076
Posted: Sun Mar 29 01:00:21 1987
Date-Received: Sun, 29-Mar-87 17:54:04 EST
References: <317@aucs.UUCP> <318@aucs.UUCP>
Distribution: na
Organization: Carnegie-Mellon University, CS/RI
Lines: 51

In article <318@aucs.UUCP>, peter@aucs.UUCP writes:
> In 4.3BSD Unix C there is a macro called "unix" which may be used to
> control compilation. E.g:
> 
>     #ifdef unix
>         ... do some unix dependent stuff ...
>     #else
>         ... do some generic stuff ...
>     #endif
> 


  Excuse me if I am misunderstanding your question, but conditional
compulation (#ifdef, #ifndef and #if) is or at least should be support
by every C compiler.

   example :
.
.
#ifdef DEBUG
    printf("size %d\nn",size);
#endif
.
.

 If you compile your code using -D option (cc -DDEBUG) the debugging code
will be included.  Nothing is sacred about the variable DEBUG.  You
can also do things like:

#ifndef TRUE
#define TRUE  1
#endif

where if the macro TRUE is not defined already, it will be now.
This will avoids all those anoying macro whatever is redefined messages
from the compiler.


  If your question is however, does every unix compiler automatically define
'unix' for you, I do not know.

				

-- 
					Eddie Wyatt

Those who know what's best for us-
Must rise and save us from ourselves
Quick to judge ... Quick to anger ... Slow to understand...
Ignorance and prejudice and fear [all] Walk hand in hand.
					- RUSH