Re: Ada array vs C pointer (call by reference)

[Robert A Duff <bobduff@shell01.TheWorld.com>]

Adam Beneschan <adam@irvine.com> writes:

> On Jun 27, 3:14 pm, Keith Thompson <ks...@mib.org> wrote:
>> It doesn't *mandate* the representation used by the C compiler; the
>> author of the Interfaces.C implementation has to *know* the
>> representation used by the C compiler.
>
> Which is, of course, impossible without a crystal ball.

No need for crystal balls.  Just read the documentation of the C
compiler.

Maybe you're worried that the C compiler will change the size of float
in a future version?  Well, first of all, that won't happen because it
will break existing C programs.  But if it does, then that's a new and
different implementation of C, and the Ada compiler would have to be
modified in order to support interfacing to it.  Why is that a problem?

This whole argument started because somebody wanted to use Float instead
of C_Float.  But there is nothing in the Ada RM saying that Float should
correspond to anything in particular.  There IS something in the RM
saying that C_Float corresponds to float as implemented by the C
compiler(s) that the Ada compiler claims to support interfacing to.
And the Ada compiler documentation will tell you which C compiler(s)
are supported.

- Bob