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From: dant@tekla.TEK.COM (Dan Tilque;1893;92-789;LP=A;60HC)
Newsgroups: comp.lang.c
Subject: Re: goto's and switch statements -- mild proposal
Message-ID: <2182@zeus.TEK.COM>
Date: Tue, 11-Aug-87 05:54:33 EDT
Article-I.D.: zeus.2182
Posted: Tue Aug 11 05:54:33 1987
Date-Received: Wed, 12-Aug-87 07:22:15 EDT
References: <855@tjalk.cs.vu.nl> <2683@hoptoad.uucp> <916@haddock.ISC.COM>
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Reply-To: dant@tekla.UUCP (Dan Tilque)
Organization: First National Security Trust Bar and Grill
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>John Gilmore writes:
>>What bothers me is that I can't say ["goto default" and "goto case N"].

Karl Heuer writes:
>It's interesting that this restriction exists, in view of the oft-stated claim
>that the reason that switch statements have automatic fallthrough (rather than
>automatic breakswitch) is that "case labels are just like real labels".

I would guess that the restriction is there to discourage the use of goto's.
I've never thought of cases as labels, but then I've never used a label in
C.  Cases certainly don't have the same syntax as labels.

>	it should be illegal to fall
>into a label (one must instead write "goto foo; foo:"); and switch statements
>should automatically break at the end of each case (thus freeing the keyword
>"break" for loop exit exclusively).  Oh yes, this also requires a new notation
>for multiple cases ("case '0'..'9':" or whatever).
>
I'd be hard put to come up with a better notation for:

	switch (c) {

	case CR:			/* assume appropriate #defines */
	case LF:
	case TAB:
	case ' ':
		/* whatever */
		.
		.
		.
These 4 values are not contiguous.  On possibility is to separating them
with commas:

	case CR, LF, TAB, ' ':

which changes the meaning of the comma operator.  Probably not a good idea.

However, I agree that it's bad programming to have this kind of thing:

	case 'a':
		a = b + count;
	case 'b':
		count += 2;
		.
		.
		.
Lint should definitely give warning since it's almost always the case that
what's desired is a break before case 'b':.  Also, one of my more frequent
mistakes is leaving breaks out of switches.


---
Dan Tilque
dant@tekla.tek.com  or dant@tekla.UUCP