Re: Array Help?

[Robert A Duff <bobduff@shell01.TheWorld.com>]

Adam Beneschan <adam@irvine.com> writes:

>   type Integer_Array is array (Integer range <>) of Integer;
>   A : Integer_Array (2 .. 7);

Right, and this is a rich source of bugs.  You usually want
arrays to start at 1, or sometimes 0 (assuming the index type
is a signed integer type, which is almost always the case
for unconstrained arrays).  In Ada 2012, you can say:

    type Integer_Array is array (Positive range <>) of Integer
        with Dynamic_Predicate => Integer_Array'First = 1;

or:

    type Integer_Array is array (Natural range <>) of Integer
        with Dynamic_Predicate => Integer_Array'First = 0;

Now 'Last can be anything you like, but 'First is fixed.

In GNAT, you can write "Predicate" instead of "Dynamic_Predicate".

- Bob