C bites / programming style [if (cond); statement;]

[Roy Smith]

> 	I avoid getting bitten in this way by ALWAYS using {}'s after
> if, while, etc.  Even when I have a null statement as the body [...]
> -Michael Shannon (hplabs!oliveb!3comvax!mikes)

	Since I was the original poster of this particular bite, let me
add a few random comments.  First off, I'm really kind of amazed how much
discussion this is getting.  I wish people would pay this much attention
when I do things correctly!

	Oddly enough, part of the bite was from emacs.  Since the code in
question was repeated several times with small changes, I wrote it once and
used a macro to duplicate and modify it each time.  My real goof was in
defining the emacs macro.  I somehow dragged the extra semi-colon along
causing an error I probably wouldn't have made if I wrote each fragment by
hand.  Shows me to try and be clever.

	I put null loop-bodies on a separate line like in the following
example.  You all know how I write null if-bodies. :-)

		while (eatup() != '\n')
			;

	If the body of the [whatever] is a single simple statement, I leave
out the braces and do something like the following (I'm using "simple" in
the generic sense, not strictly as defined by the C grammer):

	if (foo >= bar)		|	while (*foo++ == bar)
		sum += foo;	|		printf ("still a bar\n");
	else			|
		toosmall++;	|

	If the body is more complicated than an assignment or function
call, I put it in braces, even though they really aren't needed, thus:

	while ((foo = getfoo()) != EOF)	|
	{				|       for (x=0; x <= 10; x++)
		if (foo >= bar)		|       {
			sum += foo;	|               for (y=0; y <= 10; y++)
		else			|                       sumxy += x * y;
			toosmall++;	|       }
	}				|

	The entire "if-else" or "for" construct is a single statement, but
intuitively I think about lines and statements being the same (probably a
holdover from my Fortran days).  If I write a multi-line statement, I put
braces around it to make that clear (to myself, if nobody else).  Actually,
in the "for" example above, I would probably drop the braces.  If, however,
the inner loop needed braces, the outer one would be sure to get them too.

	A few people have suggested I run my source through a code grinder
like "cb".  If the output of cb is different from its input, it's a hint I
goofed somewhere.  Something like "cb < foo.c | diff foo.c -" would do the
job nicely.  While this is a good idea, I don't see why this isn't built
into "lint".

	OK, now can we please start working on somebody else's boo-boos?
It's embarrassing to see my dirty laundry come back at me 6 times a day,
even if it is somewhat amusing.
-- 
Roy Smith <allegra!phri!roy>
System Administrator, Public Health Research Institute
455 First Avenue, New York, NY 10016