Re: Easy question about Character manipulation

["(see below)" <yaldnif.w@blueyonder.co.uk>]

On 30/1/07 01:43, in article 1170121405.6329.89.camel@localhost, "Georg
Bauhaus" <bauhaus@arcor.de> wrote:

>> On the contrary, this *exactly* like (ISO Standard) Pascal.
> 
> I don't think so, if a Pascal compiler is supposed
> to determine "the same type" (exact same type) by looking
> at the definition, not the name. Otherwise two compilers
> claiming to support ISO Pascal are broken:

Trust me, I was one of the team that wrote the standard. 8-)

> program p;
> 
> type 
>    T = 1 .. 3;
>    S = 1 .. 3;
> var
>    x : T;
>    y : S;
> begin
>    x := y;   { fine in Pascal }
> end.
> 
> This program seems to be Standard Pascal, and compiles.

This does not imply that S and T are considered to be the same type.
(See below.)

> The corresponding Ada program will not compile:
> 
> procedure p is
>    type T is range 1 .. 3;
>    type S is range 1 .. 3;
>    x : T;
>    y : S
> begin
>    x := y; -- not the same type, compilation error
> end;

This is not a matter of type equivalence,
it is a matter of automatic type conversion on assignment
(assignment compatibility), and that IS unlike Ada, of course.
 
It would work just as well in Pascal if S were 1..3 and T were 2..4,
and these are obviously not the same type.

(There are further classes of compatibility in other Pascal contexts.)

-- 
Bill Findlay
<surname><forename> chez blueyonder.co.uk