Path: utzoo!mnetor!uunet!husc6!rutgers!mcnc!rti!xyzzy!throopw
From: throopw@xyzzy.UUCP (Wayne A. Throop)
Newsgroups: comp.lang.c
Subject: Re: Address of Array
Message-ID: <502@xyzzy.UUCP>
Date: 23 Dec 87 19:20:56 GMT
References: <3420@tut.cis.ohio-state.edu>
Organization: Data General, RTP NC.
Lines: 43

> lvc@tut.cis.ohio-state.edu (Lawrence V. Cipriani)
> Summary: do I have it right now?

Yep.  But I can't resist clarifying one little nit.
Something in my upbringing, I think.

> 2) The name of an array is a synonym for the address of
>    the first element of the array.  This is only a CONVENIENCE
>    so you can write:
> 	for (p = name; p < &name[NTHINGS]; p++);
>    instead of having to write:
> 	for (p = &name[0]; p < &name[NTHINGS]; p++);

This is *right*, sort of, but I wouldn't put it this way, and putting it
this way gives me an itchy sensation I just have to scratch.

The way I think of it is not that an array name is a synonym for the
address of the first element of the array, but that any array object,
when encountered in an expression, is converted to the address of the
first element in the array (except when object of sizeof or '&'
operators).  Note: "is converted", not "is a synonym".  This way of
thinking about it handles arrays of arrays nicely, while the alternate
requires one to consider aa[N] to be the "name" of an array, which is
not quite right.  A small nit, perhaps, but I think it helps to think of
it this way.

Further, this isn't so much a convenience as it is a direct fallout of
the definition of the subscripting/address-arithmetic equivalence in C.
Personally, I would have done it just the way Larry describes above, and
define pointer arithmetic in terms of array subscripting.  But K&R in
their wisdom did the reverse: subscripting is defined in terms of
pointer arithmetic.  This means that an array object, when used in a
subscripting expression, *MUST* be converted to the address of the first
element of the array for the subscript operation to work at all.  K&R
just extended this to become the default situation: array objects in
most expressions are converted as they are in subscript expressions.
Again, a small nit, but [etc, etc].

--
There are some forms of insanity which, driven to an ultimate
expression, can become new models of sanity.
                        --- Bureau of Sabotage {Frank Herbert}
-- 
Wayne Throop      <the-known-world>!mcnc!rti!xyzzy!throopw