Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!allegra!mit-eddie!genrad!panda!teddy!jpn
From: jpn@teddy.UUCP (John P. Nelson)
Newsgroups: net.lang.c
Subject: Re: goto jumps into loops
Message-ID: <2517@teddy.UUCP>
Date: Fri, 18-Apr-86 18:23:36 EST
Article-I.D.: teddy.2517
Posted: Fri Apr 18 18:23:36 1986
Date-Received: Sun, 20-Apr-86 16:45:51 EST
References: <69@brl-smoke.ARPA>
Reply-To: jpn@teddy.UUCP (John P. Nelson)
Organization: GenRad, Inc., Concord, Mass.
Lines: 43

>Can any of you
>figure out a way to do this elegantly without the goto?

Wow!  That code was UGLY!  How about this:

#include "nastydefs"
#define MAX NUM_KEYWORDS

/* This routine should print out a list of the members of List, with adjacent
 * members shown contracted as N-M, where N and M are the bounds of a range of
 * members.
 */
wrtlist(listp)
register set *listp;
    {
    register int i;

    /* scan entire set */
    for (i = 1; i < MAX; ++i)	/* note: could just as easily start at 0 */
	{
	if (in(i, listp))
	    {
	    /* this is the start of a run (potential 1 element run) */
	    printf("%d", i);

	    /* check for two in a row */
	    if (++i < MAX && in(i, listp))
		{
		/* at least two in the run - scan to the end */
		for (++i; i < MAX; ++i)
		    if (!in(i, listp))
			break;
		printf("-%d", i - 1);
		}
	    }
	/* current i is known to NOT be in the set */
	}
    }

I assumed that the "in" function was expensive - any element is only checked
ONCE.  The secret is that the outermost level loop index is modified.  A
version with an auxiliary index is also possible, which is possibly slightly
cleaner.