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From: garys@bunker.UUCP (Gary M. Samuelson)
Newsgroups: comp.lang.c
Subject: Re: How can I use #define to make something completely disappear?
Message-ID: <3037@bunker.UUCP>
Date: Thu, 5-Nov-87 09:26:28 EST
Article-I.D.: bunker.3037
Posted: Thu Nov  5 09:26:28 1987
Date-Received: Tue, 10-Nov-87 05:34:28 EST
References: <10083@brl-adm.ARPA> <850@tut.cis.ohio-state.edu> <9187@mimsy.UUCP>
Reply-To: garys@bunker.UUCP (Gary M. Samuelson)
Organization: Bunker Ramo, an Olivetti Company, Shelton, Ct
Lines: 43

In article <9187@mimsy.UUCP> chris@mimsy.UUCP (Chris Torek) writes:
>I suggest instead
>
>#define	DBPRINT(arglist) if (dflag == 0) /* void */; else printf arglist

>so that you can use, e.g.,

>	if (it was minor)
>		DBPRINT((...));
>	else
>		abort(...);
>
>without having the `else' wind in up the wrong place.

Other possible ways to avoid 'else' problems:

	if (it was minor)
	{
		DBPRINT((...));
	}
	else
	{
		abort(...);
	}

I often surround 'then' and 'else' statements with braces, even if
there is only one statement there.  BUT I do not want to start more
discussions on the use or non-use of braces.  I already know how to
use them the *right* way. :-)

Instead, I offer yet another debug macro:

#define	DBPRINT(arglist) {if (dflag) printf arglist;}

Now there will be no problem with else's.
Note that this one should be invoked without a trailing semicolon:
	DBPRINT((...))

Or:

#define DBPRINT(arglist) (dflag ? printf arglist : 0 )

Gary Samuelson