From: utzoo!decvax!decwrl!sun!megatest!fortune!sri-unix!perry.gatech@Udel-Relay
Newsgroups: net.unix-wizards
Title: Re:  if statement ambiguity and the C preprocessor
Article-I.D.: sri-unix.3729
Posted: Sun Oct 10 00:56:39 1982
Received: Sun Oct 17 22:50:08 1982

From:     Perry Flinn <perry.gatech@Udel-Relay>
Date:     29 Sep 82 11:45:02-EDT (Wed)
References: pyuxll.282, rabbit.764

The problem arises (for example) when you want to replace a function
call with a macro but you don't want to trace down all existing
invocations of that function to remove the terminating semicolon.
Lets say you have the following:

	if (status != 0)
		dprintf("Error %d\n", status);
	else
		some_other_statement;

Now if you replace the function dprintf with a macro:

	#define dprintf(a,b)	{ if (debug) printf(a, b); }

this expands into:

	if (status != 0)
		{ if (debug) printf("Error %d\n", status); };
	else
		some_other_statement;

which leaves you with an orphaned else.