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From: chongo@nsc.uucp (Curt Noll)
Newsgroups: net.lang.c
Subject: Re: "Break" and other ways out of loops and switches
Message-ID: <357@nsc.uucp>
Date: Wed, 24-Aug-83 16:04:10 EDT
Article-I.D.: nsc.357
Posted: Wed Aug 24 16:04:10 1983
Date-Received: Fri, 26-Aug-83 03:42:32 EDT
References: <302@ihuxq.UUCP>
Organization: National Semiconductor, Sunnyvale
Lines: 59

>	...  A high school student (!) that I help with his compiler over
>	occassional lunch hours came up with what I think is a super way out of
>	the multiple-level or multiple-construct break problem (i.e., breaking
>	out to the "right" level (the one you want)). He suggested labelling the
>	initial statement of the construct to be "broken" ... and then giving
>	the label as an "argument" to break.
>	... other languages (such as BLISS) have this feature. I think that
>	it's great, would be relatively easy to add to compiler (I think),
>	and is even compatible with the current C. Multiple-level breaks are
>	a common reason for seeing one of those rare goto's in modern code.
>	This feature would eliminate the need those occurrances. Well,
>	what do do you think, yea or nay?
>	
>					Chris Scussel Bell Labs

i say NAY to the high school suggestion regarding labeled multi-break.
what that would do is to create another quasi-goto, and another
way for obscene code to be created.

try:
/* more or less minus possible typos */
#define TRUE 1
#define FALSE 0
#define breakout( breakflag ) if ( breakflag ) { break; }
#define multibreak( breakflag ) breakflag = TRUE; break
#define setbreak( breakflag ) breakflag = FALSE
#define testbreak( breakflag ) ! breakflag
#typedef unsigned char BREAKFLAG
...
	BREAKFLAG stopreading;	/* read process termination */
	...

	/* read lines of text ... */
	for ( setbreak( stopreading );  some-code;
	    some-code && testbreak( stopreading ) ) {
		...

		/* character in line processing */
		while ( some-code && testbreak( stopreading ) ) {
			...

			/* case in char in a line */
			switch ( some-code ) {
			...
			case SOMETHING:
				...

				multibreak( stopreading ); /* stop reading */
				break;			/* for readability */
			...
			}
			breakout( stopreading );	/* termiate loop */
		}
		breakout( stopreading );	/* terminate loop */
	}

any number of ways can be constructed in C to do similar things.

chongo /\../\