Delphi “array of const” to “varargs”

Question

Please help! I need this conversion to write wrapper for some C headers for Delphi.

As an example:

function pushfstring(fmt: PAnsiChar): PAnsiChar; c         


        

Answer 1

The wrapper you are trying to write is possible in Free Pascal, since Free Pascal supports 2 equvalent declarations for varargs external functions:

http://www.freepascal.org/docs-html/ref/refsu68.html

so instead of

function pushfstring(fmt: PAnsiChar): PAnsiChar; cdecl; varargs; external;

you should write

function pushfstring(fmt: PAnsiChar; Args: Array of const): PAnsiChar; cdecl; external;

Update: I have tried the same trick in Delphi, but it does not work:

//function sprintf(S, fmt: PAnsiChar; const args: array of const): Integer;
//           cdecl; external 'MSVCRT.DLL';

function sprintf(S, fmt: PAnsiChar): Integer;
           cdecl; varargs; external 'MSVCRT.DLL';

procedure TForm1.Button1Click(Sender: TObject);
var
  S, fmt: Ansistring;

begin
  SetLength(S, 99);
  fmt:= '%d - %d';
//  sprintf(PAnsiChar(S), PAnsiChar(fmt), [1, 2]);
  sprintf(PAnsiChar(S), PAnsiChar(fmt), 1, 2);
  ShowMessage(S);
end;