Re: Two dimensional array Question

mdh wrote:
> I am still having a problem understanding K&RII on p 112. I have
> looked at the FAQs --which I am sure answer it in a way that I have
> missed, so here goes.
> A 2-dim array, (per K&R) is really a 1-dim array, each of whose
> elements is an array.
> Looking at the debugger I use, arr[2][13] is shown as an initial value
> of "2", but when expanded, there are 2 consecutive arrays of 13
> elements.
> So, may I ask this?
> Is there anything special that marks the end of the first 13 elements
> from the beginning of the 2nd 13 elements? In other words, it seems to
> me that this is nothing more than a 1-dim array, with the information
> about the structure of the array provided by the declaration?
> Hopefully this makes sense.
> 
Perfect sense. All above is correct. Given 'int arr[2][13];', arr is an 
array 2 of array 13 of int. 26 consecutive ints.

> The exercise associated with this, used the construct
> 
>  *p = arr[1 or 0 ] to point to either the "first" or "second" row of
> the array. Does the compiler "know" where to point to because it has
> been given this information by the declaration of "13" in arr[2][13].
> Hopefully this makes sense too!
> 
No. arr[0] is (the address of) an array 13 of int. The pointer 'p' must 
be declared to reflect this.

   int (*p)[13];

Now p is a pointer to array 13 of int and..

   p = arr[0];

...makes sense.
> 
> And lastly, K&R's description of "each of whose elements is an array"
> has never made sense to me. It may be that the answer to the above may
> clarify it.
> 
I hope so. You're really not too far off. Hang in there.

> Thanks in advance.

-- 
Joe Wright
"Everything should be made as simple as possible, but not simpler."
                     --- Albert Einstein ---