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From: throopw@xyzzy.UUCP (Wayne A. Throop)
Newsgroups: comp.lang.c
Subject: learning C declaration syntax
Message-ID: <223@xyzzy.UUCP>
Date: Tue, 25-Aug-87 17:04:01 EDT
Article-I.D.: xyzzy.223
Posted: Tue Aug 25 17:04:01 1987
Date-Received: Thu, 27-Aug-87 01:42:47 EDT
References: <8877@brl-adm.ARPA> <8088@mimsy.UUCP> <1623@tekchips.TEK.COM> <956@bc-cis.UUCP>
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Lines: 54

> john@bc-cis.UUCP (John L. Wynstra)

> Sure it's nice now to see the same thing in the declaration as in the
> procedural text, and aids like typedef help reduce the problem, but it
> took me a long time to figure out the "inside-out" logic required to
> read C declarations, and an especially nasty one, like the (*b)[10]
> discussed in the net now, will still throw me a little (I write it down
> and puzzle it out).

This is a widespread reaction to C declaration syntax, and in many ways
I can see the point.  I thought it arbitrary and bizarre until I read
the explanatory note in the K&R tutorial which states that declaration
syntax mimics expression syntax.  But once one knows this about
declarations, why is it still difficult?  After all, are assignments
like

        *a1[n] = 23;
or
        (*a2)[n] = 23;
or
        i = (*a3[n])();

confusing?  Surely it isn't really hard to figure out that a1 is an
array of pointers to int, a2 is a pointer to an array of int, and a3 is
an array of pointers to functions returning int?

Note that I think C's declaration syntax *is* indeed misguided and
counterintuitive, especially since this rule is violated (for good
reason, which is the point) for structure, enum, and union declarations.
But once one knows the rule, why is it still difficult to parse
declarations?  The question boils down to: Is traditional expression
syntax for indirection, subscription, and function invocation hard (for
humans) to parse, and is that the reason C declarations are hard (for
humans) to parse?  If this is so, what does this say about such
expressions in general?  Does there need to be a cexpr that does for
expressions what cdecl does for declarations?  Was COBOL right to spell
things out in pseudo-english?

        SUBSCRIPT a3 BY n AND INDIRECT THAT AND INVOKE THAT GIVING i.
or
        EVALUATE 23 GIVING INDIRECT a2 SUBSCRIPTED BY n.
or
        EVALUATE 23 GIVING SUBSCRIPT a2 BY n AND INDIRECT THAT.

After all, this is the expression-like equivalent to what people seem to
perfer for declarations.  

I'm not trying to be sarcastic... just wondering.

--
"That saw isn't very sharp."
                --- Comment by the Marquis of Angelsey to the doctor
                    amputating his leg.
-- 
Wayne Throop      <the-known-world>!mcnc!rti!xyzzy!throop%e