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From: James Kuyper <jameskuyper@alumni.caltech.edu>
Newsgroups: comp.lang.c
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Date: Wed, 10 Jul 2024 02:38:39 -0400
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On Sat, 6 Jul 2024 19:53:56 +0100, bart wrote:

> On 06/07/2024 19:28, James Kuyper wrote:
>
>> ... an expression that has type "array of type" is
>> converted to an expression with type "pointer to type" that points to
>> the initial element of the array object ..." (6.3.2.1p3).
> 
> This is really, really pedantic. Even gcc doesn't get it right in that
> case, because if I try and compile this:
> 
>      int a, b>      a[b];
> 
> it says:
> 
>    error: subscripted value is neither array nor pointer nor vector

There is no expression that has the type "array of type" in the above
code. How is that relevant to what I wrote?

For the subscript operator:
"One of the expressions shall have type "pointer to complete object
type", the other expression shall have integer type," (6.5.2.1p1)

Neither a nor b has the type "pointer to complete object type". Both a
and b have the type 'int'. How did you expect that code to be meaningful?

Note that a[&b] would be valid, since &b is treated for this purpose as
a pointer to the first element of a 1-element array.

Note that the standard doesn't mandate which expression have the pointer
type; that's because a[&b] is defined as *(a + &b), and you can add a
pointer to an integer in either order, so you can subscript an array as
array[5] or 5[array].

> 'Subscripting' I think we can agree is the same thing as 'indexing':
> what those funny square brackets do.

I can agree that subscripting is indeed what those square brackets do.
The C standard never mentions indexing, but I do agree that there is a
correspondence. However, if you derive any conclusions from that
correspondence that contradict what the C standard says about
subscripting, those conclusions are invalid.