Re: address/access/pointer confusion

[Georg Bauhaus <sb463ba@l1-hrz.uni-duisburg.de>]

skidmarks <aschwarz@acm.org> wrote:


:               p1 : System.Address := a(0)'Address;
not necessarily, I think.

And you also need to declare that a's components may be aliased,
using the same keyword "aliased" as you did for a, for the Integers in a.

When you compare C pointers to Ada arrays, the set
of attributes and array operations is largly missing in C.
(They are available in Ada, even for identifiers indirectly
denoting an array, as you have indicated.)

  a'range

for example.


:               -- p /= p1 in general
:               -- One representation of 'a' could be:
:               -- a  => <<size of a><pointer to space for a>> --> a(0)
:               -- p  => points to the 'a' dope vector (above)

AFAIK, dope info cannot always be assumed to be near addressing cells.
I think the GNAT docs, for example, speak about this in the
section on string access, using either fat or thin pointers.


-- Georg