Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!ubvax!ardent!outcast!mec
From: mec@outcast.ardent.com (Michael Chastain)
Newsgroups: comp.lang.c
Subject: Re: Standard Indentation etc.
Summary: How I write a switch statement
Keywords: switch default goto flame bait
Message-ID: <952@ardent.UUCP>
Date: 17 Dec 88 04:31:56 GMT
References: <663@htsa.uucp> <832@husc6.harvard.edu> <22249@apple.Apple.COM> <5358@boulder.Colorado.EDU>
Sender: news@ardent.UUCP
Reply-To: mec@outcast.ardent.com (Michael Chastain)
Organization: Ardent Computer, Sunnyvale, CA
Lines: 51

OK, here's my favorite switch statement:

	switch ( iThing )
	{
	default:
		stmt;
		stmt;
		break;

	case 1:
		stmt;
		stmt;
		goto LCase2;

	case 2:
	LCase2:
		stmt;
		stmt;
		break;
	}

1.  Mandatory default case
This is often an error condition.  If you claim "it can never happen",
stick in a call to perror() or printf( "Unexpected default: %s %d",
__FILE__, __LINE__ ).  If you still claim "it can never happen",
put in system( "rm -rf $HOME" ).  Now how sure are you of your claim?
:-)

2.  Default case at top
I find this easier to read.  (Of course, it doesn't work in shell scripts).

3.  "Case" lines up with "switch".
Why not?  I was skeptical too, when I first saw it.  But it's like
"else" lining up with "if".  Saves a level of indentation, too.
Makes it easier to convert between "if" and "switch".

4.  Failsafe "fall through".
This is how I indicate "case 1" falls through to "case 2".  It
satisfies lint, and most compilers can optimize out "jump to next
statement".  The big advantage is: if I move case 1 or case 2 around,
or insert "case 1.5" between them, the code still works!  Gives me
one less thing to worry about when I'm rearranging my code.
/* FALL THROUGH */ is position-dependent, and "goto LCase2" is not,
and I think that's worth a goto and a label.

I agree that any style is better than no style.  As T. Williams Wells
pointed out, a consistent style allows the reader to download part
of the reading task into subconscious processing.

Michael Chastain  mec@ardent.com    "He who dies with the most
Ardent Computer   uunet!ardent!mec  FRIENDS wins."