Re: Types, subtypes and ranges

["David C. Hoos, Sr." <david.c.hoos.sr@ada95.com>]

Because TTT'Image is inherited from its base type T.

If you had declared TT and TTT as new T types, the constraint
error would have occurred, but then you wouldn't have been
able to add anders to banders without type conversion, because
the types would have been distinct.

"Anders Wirzenius" <anders.wirzenius@pp.qnet.fi> wrote in message
news:V4%q6.26$OG2.2999@read2.inet.fi...
>
> Mark Lundquist wrote in message ...
> >Sorry for the late response (I lost access to news for a while...)
> >
> >WM <wwminirl@hotmail.com> wrote in message
> >news:97pfmt$ll30@tech.port.ac.uk...
> >> Hi, I am an ada beginner. Can anyone kindly tell me what's the
difference
> >> between TYPE and SUBTYPE?
> >
> ...
> >    subtype S is T;
> >
> >declares a new subtype S of the type of subtype T.  This is also an
example
> >of a subtype declaration that does not include a constraint, so the
> >constraint of S is the same as the constraint of T.  (This is how you
> >"rename" or create an alias for a type).  What a subtype declaration
looks
> >like that adds a constraint depends on the type of the subtypes, e.g. for
> an
> >integer type you might have
>
> May I continue with two more questions:
> 1.
> given
> >
> >    subtype S is T range 1 .. 10;
>
> what is the the difference between the above declaration and
> type S is new T range 1..10;
>
> 2.
> Why don't I get a constraint_error in the following code where I violate
the
> range of type TTT in the Put statement?
>
> with Ada.Text_IO;
> procedure Why_Not_Constraint_Error is
>    type T is new Integer;
>    subtype TT is T range -2..-1;
>    subtype TTT is T range -1..-1;
>    anders : TT := -2;
>    bnders : TTT := -1;
>    use Ada.Text_IO;
> begin
>    Put ( TTT'Image ( anders+bnders ) );
> end Why_Not_Constraint_Error;
>
> Anders
> another beginner
>
>
>