Re: Ada Hash

[Matthew Heaney <matthewjheaney@earthlink.net>]

markp <markwork66@yahoo.com> writes:

> I need to use a hash table to store data using an integer as the key.
> I would like to use Ada.Containers.Hashed_Maps. Is there a default
> hash function for an integer that I can supply to the instantiation
> and could somebody provide a quick sample piece of code to do this?

You just need an identity function, as Randy pointed out:

  function Hash (N : Natural) return Hash_Type is
  begin
     return Hash_Type (N);
  end;

If your integer subtype has negative values, then you could do something like:

  function Hash is
    new Unchecked_Conversion (Integer, Hash_Type);

You could also use one of the ordered forms directly.  Integer subtypes have a
less-than relational operator by default, so there's nothing else you would
need to do.