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From: bart <bc@freeuk.com>
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Subject: =?UTF-8?Q?Re=3A_technology_discussion_=E2=86=92_does_the_world_need?=
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Date: Wed, 10 Jul 2024 10:58:30 +0100
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On 10/07/2024 07:38, James Kuyper wrote:
> 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.

My post was about what gcc says. Your point I believe was about the fact 
that indexing / subscripting can only be meaningful with a pointer type, 
according to C, and not an 'array' or 'vector'.

But gcc does mention subscripting in connection with arrays and vectors.

So /my/ point is that sometimes it is helpful not to be so strict if it 
helps understanding.