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From: chris@umcp-cs.UUCP (Chris Torek)
Newsgroups: net.lang.c
Subject: Re: break, et cetera
Message-ID: <2248@umcp-cs.UUCP>
Date: Sun, 17-Nov-85 21:38:58 EST
Article-I.D.: umcp-cs.2248
Posted: Sun Nov 17 21:38:58 1985
Date-Received: Mon, 18-Nov-85 08:12:22 EST
References: <771@whuxl.UUCP> <9500030@iuvax.UUCP> <2246@umcp-cs.UUCP>
Organization: U of Maryland, Computer Science Dept., College Park, MD
Lines: 40

Darn...  when I got up this evening I realized that I had not really
said what I wanted to in the first part of that article.  I hate
to reopen the wound and rub in salt, but . . . here goes:

Given a C construct such as

	for (init; cond; step) {
		code;
		if (cond2)
			break;
		code2;
	}

one can, without changing the meaning of the code, write

	init;
	bool := true;
	while (cond) and bool do
	   begin code;
	   if cond2 then
	      bool := false
	   else
	      begin code2;
	      step
	      end
	   end;

which is how the loop would most likely appear in Pascal.  (The
expanded form if `code' or `code2' contains `continue' statements
is somewhat different, but does exist.)  This expanded form can be
transformed direcly into C in the obvoius way.

These are semantically equivalent when it comes to proving the code
correct.  Since they are equivalent, you may elect to use either
form.  In C, I would use the `compressed' form; but this is a matter
of taste, and you probably know the old expression concerning such.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 4251)
UUCP:	seismo!umcp-cs!chris
CSNet:	chris@umcp-cs		ARPA:	chris@mimsy.umd.edu