Hi,

I have a procedure defined as follows:

procedure Copybytes(var dst: array of Char; src: array of Char; len: integer);

If I call it using the following:

Copybytes(@dst[dloc], at src[sloc],16);

I get an error:

dwg.pas(116,36) Error: Incompatible type for arg no. 2: Got "Pointer",
expected "Open Array Of Char"

Can anyone suggest a solution?

Kind Regards,

Dave Coventry

What's the type of dst and src that you pass to the function? Array is not pointer, and I have no idea about open array with var modifier. Open array is compatible with any array (and its subarrays through slicing).

Hi, thanks for the response.

leledumbo wrote

What's the type of dst and src that you pass to the function? Array is not pointer, and I have no idea about open array with var modifier. Open array is compatible with any array (and its subarrays through slicing).

dst and src are passed to the function that calls Copybytes();
function copy_compressed_bytes(var dst: array of Char; var dloc, sloc:
integer; src: array of Char;
  len: integer): integer;
begin
  Copybytes(@dst[dloc], at src[sloc],16);
  return 0;
end;

You may be onto something. dst is passed as a *var* because I'm interested in the destination array but can discard the src after it's been read.

I'll look into how the memory is allocated for src.

Many thanks.

Dave

I think making src also a var parameter and structuring the signatures for the routines without @ as follows will work:

procedure Copybytes(var dst, src: array of Char; len: integer);
...
function copy_compressed_bytes(var dst: array of Char;
                                var dloc, sloc:integer;
                                src: array of Char;
                                len: integer): integer;
begin
   Copybytes(dst[dloc],src[sloc],16);
   Exit(0);
end;

I think making src also a var parameter...

Or const since it's meant to be read only

leledumbo wrote

Or const since it's meant to be read only

Hmmm.

Doesn't help. Still getting the same error.

I've tried passing the src parameter as a Pointer and then casting it as an array of Char.

procedure Copybytes(var dst: Pointer; src: Pointer; len: integer);
var
  i: integer;
  data_in,data_out: Array of Char;
begin
  ;
  ;
  for i:=0 to len-1 do
  begin
    data_out[i]:=data_in[i];
  end;
end;
Calling the procedure:     Copybytes(@dst[dloc], at src[sloc],16);

I get the error

Error: Can't assign values to an address

One source of confusion arises because your parameter declaration "array of char" in procedure Copybytes(var dst: array of Char ... means something different from your variable declaration

var
  data_in, data_out: Array of Char;

where "Array of Char" denotes a dynamic array - rather different from the parameter-passing declaration.

Actually, rather than continuing this, if what you need is only to copy a dynamic array then you can simply:

dst := Copy(src,0,Length(src));

leledumbo wrote

dst := Copy(src,0,Length(src));

Thank you.

It's not quite that simple, but I'll bear that technique in mind. :+)

dst:=Copy(src);

works as well.