Re: Pointer

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Mon, 19 May 2008 11:31:57 +0000, S�bastien wrote:

>> procedure To_String (Pointer : in System.Address; Length : in Natural)
>> return String is
>>    Result : String (1 .. Length);
>>    for Result'Address use Pointer;
>>    pragma Import (Ada, Result); -- suppress default initialization
>> begin
>>    return Result;
>> end To_String;
>> 
>> But Dmitryi's solution is safer, of course. HTH
> 
> Ok, I was not clear enough. Converting char* to String is not an issue, 
> I'm using Interfaces.C.String with no problem. My problem is to convert 
> all the strings in the char** in string one by one.

Aha, it is const char *[] ...

> Something like this:
> CharPtrPtr: System.Address := MyCFunctionReturninCharStarStar;
> N: Natural := MYCFunctionTellingMeHowManyStrings;
> 
> for i in Natural range 0 .. N loop
>     -- Some ada code to convert CharPtrPtr[i] to String
> end loop;

with Interfaces.C.Pointers;
with Interfaces.C.Strings;  use Interfaces.C.Strings;
with Interfaces.C; use Interfaces.C;

type Chars_Ptr_Array is array (size_t range <>) of aliased chars_ptr;
pragma Convention (C, Chars_Ptr_Array);
package Pointers_To_String is
   new Interfaces.C.Pointers (size_t, chars_ptr, chars_ptr_array, null);
use Pointers_To_String;
...   
Data : Pointers_To_String.Pointer := MyCFunctionReturninCharStarStar;
N: Natural := MYCFunctionTellingMeHowManyStrings;
...
for Index in 1..N loop
   declare
      Element : String := Value (Data.all);
   begin
      ... -- Use the element
   end;
   Increment (Data); -- Move to the next one
end loop;

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de