Re: Implementing pointers to pointers in Ada

[mab@dst17.wdl.loral.com (Mark A Biggar)]

In article <Pine.GSO.3.93.960909230243.7142A-100000@firefly.sd.monash.edu.au> Vasilios Tourloupis <vasilios@insect.sd.monash.edu.au> writes:
>Dear Ada users,
>As the title suggests, how would I go about implementing pointers to
>pointers in Ada?
>For example, I have declared the following variable in C:
>    unsigned **a;
>How would this be expressed in Ada terms?

type unisgned is ... ;
type u_ptr is access all unsigned;
type u_ptr_ptr is access all u_ptr;

a: u_ptr_ptr;

But, as ** variables in C a most often used to walk through C arrays of
pointer with ++, and you just don't manipulate arrays in Ada that way, such
declarations almost never appear in Ada programs. It usually makes more
sense (if translating a C algorithm to Ada) to redesign the algorithm to use
array indexing, then to emulate the C double indirection.

--
Mark Biggar
mab@wdl.lmco.com