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From: sbs@valid.UUCP (Steven Brian McKechnie Sargent)
Newsgroups: net.lang
Subject: Re: null statements
Message-ID: <484@valid.UUCP>
Date: Wed, 23-Jul-86 02:09:54 EDT
Article-I.D.: valid.484
Posted: Wed Jul 23 02:09:54 1986
Date-Received: Thu, 24-Jul-86 00:18:51 EDT
References: <800015@ccvaxa> <463@opus.nbires.UUCP> <442@sunybcs.UUCP>
Organization: Valid Logic, San Jose, CA
Lines: 46

> > So to get the effect equivalent to "zero" out of the null statement, do we
> > invent some sort of "positional notation" for statements?!?!
> Fine with me!  I'd rather be able to write
> 	while ('\n' != getchar()) nothing;
> than
> 	while ('\n' != getchar()) /* do nothing */ ;
> -- 
> Col. G. L. Sicherman
> UU: ...{rocksvax|decvax}!sunybcs!colonel
> CS: colonel@buffalo-cs
> BI: csdsicher@sunyabva


Only a barbarian or Obfuscated C Contest winner would champion the use of
	#define nothing	/* do nothing */
but I figured I'd mention it anyway.

I format null-body loops so:
	while (getchar() != '\n')
		;
which fixes most of the "eyeball ambiguity."

The null statement problem is much worse in Pascal because there is no
explicit statement termination, only separation.  So

 1	IF complicated predicate involving several dozen apparently randomly
 2	   selected expressions THEN
 3		{Attempt to do nothing innocuously};
 4	ELSE BEGIN
 5		writeln('Read the code to find out what happened here.');
 6		i := i/0;
 7	END;

is a lose, lose, lose.  That ; character on line 3 makes Mr. Pascal very sick.
You can replace it with the sequence BEGIN END, which looks a little stoopid
but gets the job done.  In Berkeley Pascal we had an explicit "null" statement
that did what you want with no muss & no fuss: it worked anywhere that the
sequence BEGIN ... END did.

I sort of like the Modula-2 convention of tagging everything with an END.
It makes programs chattier than they need to be but it seems to get the
point across.  Actually, the Algol/UNIX Shell convention of if...endif,
do...done, case...esac is best of all, because you can read the code forwards
OR backwards...

S.