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From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: net.lang.c
Subject: Re: C subscripts
Message-ID: <4546@utzoo.UUCP>
Date: Sat, 27-Oct-84 19:29:37 EDT
Article-I.D.: utzoo.4546
Posted: Sat Oct 27 19:29:37 1984
Date-Received: Sat, 27-Oct-84 19:29:37 EDT
References: <195@mouton.UUCP>
Organization: U of Toronto Zoology
Lines: 52

> Who else out there thinks that
> 	some_array_name[more][long][names]
> is actually a good way to do things?

An equally-appropriate question is "who out there thinks this is a
sufficiently severe problem to be worth fixing?".

> Just as we need nested comments, because after all other "great languages"
> do, I propose that C support "normal" subscripting.

I suggest that C needs neither.

> Mathematicians have been around longer than C...

So they have, but that doesn't mean we should change C so that the
multiplication operator is implicit, like it is in math.  "They do it
that way in math" is not really a very relevant argument; we do lots of
things differently in programming languages.  Whether this is a good
thing is an interesting question, which I don't suggest debating here,
but we have ample precedent for being different.

> ... in the name of compatability, which is what the ANSI standard
> is all about anyway, the compiler SHOULD ...

Compatibility *with* *what*?  Surely not with older C implementations,
which is the major compabitility concern of the ANSI standard; I'm not
aware of any C implementation that has done this.

> Now, BEFROE the flames start I KNOW the comma operator exists.
> This is not overloading because subscripts are expressions, not statements.
> So don't start quoting K&R pg 192 to me.

"expressions, not statements"?  Surely you are confused; a C "assignment
statement" is nothing but an expression with a semicolon after it.  The
distinction you're after, I think, is the one made in things like function
parameter lists:  commas are not comma operators unless within parentheses
or other bracketing.  The expression "x[2,3]" has a perfectly legitimate
(albeit peculiar and unlikely) meaning in C right now, and you are changing
it.  It would not surprise me if somebody, somewhere, had found a use for
the current behavior; to judge by some of the furor over cleaning up the
preprocessor, there is no feature of C so slimy that someone won't find
a real use for it.  Remember that "not breaking existing correct programs"
is the specific "compatibility" objective of the ANSI C committee; you
are proposing a violation of it, for reasons that seem thin.

> p.s.  Does anyone know of a good preprocessor macro to convert
> 	[a,b,c,...n] into [a][b][c][...][n] for n>1 ?

Sounds like you could do it with sed, if things weren't too complicated.
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,linus,decvax}!utzoo!henry