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From: sanders@peyote.cactus.org (Tony Sanders)
Newsgroups: comp.lang.c
Subject: Re: Passing Variable Numbers of Arguments
Message-ID: <5270@awdprime.UUCP>
Date: 12 Feb 91 01:52:52 GMT
References: <5196@media-lab.MEDIA.MIT.EDU> <1991Feb11.225815.5875@zoo.toronto.edu>
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Reply-To: sanders@peyote.cactus.org (Tony Sanders)
Organization: IBM AWD, Austin
Lines: 38
Originator: sanders@sanders.austin.ibm.com

In article <1991Feb11.225815.5875@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes:
>For a function, you'll need to use <stdarg.h> (ANSI C) or <varargs.h> (many
>old implementations).  Can't be done with a macro at all.
This is annoying.  How do get around this problem so I can easily
eliminate debug code if NODEBUG is set (or if DEBUG isn't set, whichever).
For instance...

This works great:
#ifdef NODEBUG
#define DPV(var,type) /* Removes code like magic */
#else
#define DPV(var,type) fprintf(stderr,"%s:%d, " # var " = %" # type "\n",var);
#endif

But I can't do this:
#ifdef NODEBUG
#define DP(fmt,...) /* sigh */
#else
#define DP(fmt,...) fprintf(stderr,fmt,...);
#endif

So I do this:

#ifdef NODEBUG
#define DP(level) if (0)	/* I hope the optimizer gets rid of this */
#else
extern DebugPrint(char *,...);
#define DP(level) if (debug&level) DebugPrint
#endif
DP(1)("this fmt string %s\n","sucks rocks");


Any better ideas???

-- sanders@peyote.cactus.org
First rule of software:  Throw the first one away.
and so on...
I am not an IBM representative and I speak only for myself.