Re: Translate from C

[tmoran@acm.org]

>I've this code in C : http://www.a2lf.org/util.c
>and i want to translate it in Ada;
  In Ada one would usually have "Destination := Source;" rather than
doing a procedure call.  But if it needs to be a procedure,
  procedure Copy(Source : in Interfaces.C.char_array;
                 Destination : out Interfaces.C.char_array;
                 N : in Natural) is
  begin
    Destination(Destination'first .. Destination'first+N-1)
      := Source(Source'first .. Source'first+N-1);
  end Copy;
assuming you want to deal with C arrays rather than Ada Strings.
Of course if you wanted to handle mixed types, eg, copy a 32 bit
float to 4 8-bit chars,  your friend's solution comes close.  However,
  S : String (1 .. Bytes);
may include bounds information as well as the data.  You can avoid that
possibility by making the S and D declarations as large, fixed size,
strings, where you are careful to only touch the first Bytes bytes, eg
  S : String (Positive);  -- fixed size array needs no dynamic bound info
  D : String (Positive);
To avoid possible initialization (ie, destruction) of S and D, you should
  pragma Import(C, S);
  pragma Import(C, D);
Also, in Ada you could replace the loop
      for I in S'Range loop
         D (I) := S (I);
      end loop;
by
      D(1 .. Bytes) := S(1 .. Bytes);