Re: unsigned type

[Ludovic Brenta <ludovic@ludovic-brenta.org>]

Rob Solomon wrote on comp.lang.ada:
> I was able to use the Natural and Positive.  
>
> Now I'm trying to understand Mod types.
>
> I tried this:
> type card31 is mod 2_147_483_648;
> type card32 is mod 4_294_967_296;
> c31 : Card31;
> c32: Card32;
> LI : Long_Integer;
> and
>
> LI := Long_Integer(c32);
>
> How to I output c31 and c32?  Modula-2 uses WriteCard or CardToString
> and WriteString
>
> I tried using Put, but I got an error saying that correct procedure
> could not be found, or something like that.
>
> Put(LI) works until the value of LI > 2**31, even for c32.

Ada.Text_IO.Put_Line (Card31'Image (c31));

or

   package C31_IO is new Ada.Text_IO.Modular_Text_IO (Num => Card31);
begin
   C31_IO.Put (c31);

But I have three suggestions:

- rather than "type card31 is mod 2_147_483_648", write "type card31
is mod 2**31;"

- do not declare machine-oriented types like card31 or card32 in the
first place; instead, define application-oriented types like
"Temperature" or whatever

- before you define modular types, explain to yourself why you need
the wrap-around semantics or the bitwise operators (modular types have
them, signed integer types don't).

--
Ludovic Brenta.