Re: Ada vs Delphi?

[Ted Dennison <dennison@telepath.com>]

In article <37b129ae.43419124@news.total.net>,
  aratel@total.net (Andre Ratel) wrote:

>   type
>     n1, n2: cardinal;
>     N21, N12: integer;

> Now, with the above definitions of variables, a statement like
>     N21:= n2 - n1;
> would not be valid with Ada?

It depends on how "cardinal" is defined. If it were defined as a
completely separate type, eg:
   type Cardinal is 0..Integer'max;

then no, that would not be allowed. If you wanted to do that you'd have
to be more explicit about it. eg:
   N21 := Cardinal(n2 - n1);

And of course the type conversion would probably cause a constraint
check (unless they are turned off, or the compiler can determine ahead
of time that the check will always pass).

However, I could use a "subtype" instead of a completely different
integer type. (I'm not sure if Delphi's "cardinal" includes 0 or not,
but lets assume it does .If not, substitute "Natural" with "Positive"
below). Ada has a predefined subtype of Integer named "Natural" that
achieves the same effect. IAW, the following *is* legal Ada:
   n1, n2 : Natural;

   N21 := n2 - n1;

So the answer is, it could be either legal or not legal, depending on
how you the developer, want it to be.

--
T.E.D.


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