Re: How to pass two dimensional arrays to C

[Simon Wright <simon@pushface.org>]

"Jeffrey R. Carter" <spam.not.jrcarter@acm.not.spam.org> writes:

> So to my mind, and using the notation I've described here, the row
> elements are contiguous. So I don't know whether we agree or
> disagree.

We agree, I think.

I don't remember the last time I wrote anything to do with matrices,
which is some sort of explanation; if you have a 4x4 state transition
table it's not an issue!

with Ada.Text_IO; use Ada.Text_IO;
with System.Storage_Elements; use System.Storage_Elements;
procedure Rows_And_Columns is
   package Address_IO is new Modular_IO (Integer_Address); use Address_IO;
   type Matrix is array (Integer range <>, Integer range <>) of Integer;
   M : Matrix (0 .. 2, 0 .. 3);
begin
   for A in M'Range (1) loop
      for B in M'Range (2) loop
         Put (To_Integer (M (A, B)'Address));
      end loop;
      New_Line;
   end loop;
end Rows_And_Columns;

grendel:~/tmp simon$ ./rows_and_columns 
 3221223544 3221223548 3221223552 3221223556
 3221223560 3221223564 3221223568 3221223572
 3221223576 3221223580 3221223584 3221223588

so the last index is the one that has contiguous elements. I guess I
have never looked up 'row-major order' before.