Re: Easy question about Character manipulation

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


.

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