Path: utzoo!mnetor!uunet!husc6!bbn!bbn.com!rsalz
From: rsalz@bbn.com (Rich Salz)
Newsgroups: comp.lang.c
Subject: Re: C Quirk??
Message-ID: <413@fig.bbn.com>
Date: 17 Feb 88 18:28:32 GMT
References: <1653@ssc-vax.UUCP> <804@PT.CS.CMU.EDU> <23498@hi.unm.edu> <186@ateng.UUCP> <885@PT.CS.CMU.EDU>
Organization: BBN Laboratories, Cambridge MA
Lines: 24

=>>#define               clearline()             while (getchar() != '\n')
=> This is seriously bad code.  What if stdin reaches end of file?
=
=   It loops forever -- oops.  Change that to 
=#define clearline() while (1) {int ch = getchar(); \
=                         if ((ch == EOF) || (ch =='\n')) break; }

Not quite yet; the following "obvious" fragment won't compile
(try it before posting "why" to the net):
	if (a)
	    if (b)
		clearline();
	    else
		printf("Don't know about b, but a is zero.\n");

This should work:
#define clearline() \
	while (getchar() != '\n' && !feof(stdin) && !ferror(stdin))

As a general rule, you probably don't want to use { } in #define's
as  { }; is not the same as { }.
	/r$
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