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Path: utzoo!utcsri!greg
From: greg@utcsri.UUCP (Gregory Smith)
Newsgroups: net.lang
Subject: Re: null statements
Message-ID: <3188@utcsri.UUCP>
Date: Tue, 29-Jul-86 00:24:58 EDT
Article-I.D.: utcsri.3188
Posted: Tue Jul 29 00:24:58 1986
Date-Received: Tue, 29-Jul-86 00:42:20 EDT
References: <800015@ccvaxa> <463@opus.nbires.UUCP> <442@sunybcs.UUCP> <484@valid.UUCP>
Reply-To: greg@utcsri.UUCP (Gregory Smith)
Organization: CSRI, University of Toronto
Lines: 53
Summary: 

In article <484@valid.UUCP> sbs@valid.UUCP (Steven Brian McKechnie Sargent) writes:

>> Fine with me!  I'd rather be able to write
>> 	while ('\n' != getchar()) nothing;
>> than
>> 	while ('\n' != getchar()) /* do nothing */ ;
>
>I format null-body loops so:
>	while (getchar() != '\n')
>		;
>which fixes most of the "eyeball ambiguity."
>
Good stuff, I plan to decide on one of these practices and follow it.
C has a danger inherent in the do..while loop, some people indent them
as below:

	do{
		/* a whole lotta stuff, many lines */
	}
	while( foo_bar(*x++) != BLETCH );

Thus making it look like the last line is a null-bodied 'while'.
I ( like most ) circumvent this by writing }while(...) at the end, and
making the body a compound statement whether it needs it or not ( A loose
'do' is *scary*.... could get lost in there... bolt it to a '{' )

>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

Isn't there a null statement ""? I.e., can't you say

	IF .... THEN ELSE BEGIN ... END

??? ( i.e. just delete the ; on line 3. Sorry, can't find a reference ).
PS: a Pascal teaching compiler I once used could come up with the
message 'semicolon is never legal before ELSE'. Neat, huh?

-- 
"You'll need more than a Tylenol if you don't tell me where my father is!"
						- The Ice Pirates
----------------------------------------------------------------------
Greg Smith     University of Toronto      UUCP: ..utzoo!utcsri!greg