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From: karl@MorningStar.Com (Karl Fox)
Newsgroups: comp.lang.c,comp.unix.wizards,alt.sources,comp.sources.d,misc.misc
Subject: Re: #define DEBUG... (using printf for debugging)
Message-ID: <1990May3.200216.3705@MorningStar.COM>
Date: 3 May 90 20:02:16 GMT
References: <11290@hoptoad.uucp> <40628@cornell.UUCP>
Sender: news@MorningStar.COM (USENET Administrator)
Reply-To: karl@MorningStar.Com (Karl Fox)
Organization: Morning Star Technologies
Lines: 38
In-Reply-To: gordon@mimir.cs.cornell.edu's message of 3 May 90 14:50:35 GMT

In article <40628@cornell.UUCP> gordon@mimir.cs.cornell.edu (Jeffrey  Adam Gordon) writes:

   I want to have a DEBUG flag which controls whether diagnostic printfs
   are executed or not.

   The obvious way to do this is:

   #ifdef DEBUG
	   printf ("debugging information");
   #endif DEBUG

   But its a pain to have to type the #ifdef ... #endif all the time, and
   its less readable than simply having:

	   DEBUG ("debugging information");

   Now, I can use the latter format if I

   #define DEBUG printf

   but then how do I turn DEBUG off?


Here is a not-too-gross method I have seen suggested (and used):

    # define DEBUG(a) printf a

or, to disable it,

    # define DEBUG(a)

Then, call it with a double set of outer parentheses:

    DEBUG(("Warning: user %s has an ugly face!\n", user_name));

It even works as the THEN clause of an IF statement.
--
Karl Fox, Morning Star Technologies               karl@MorningStar.COM