How to - string in DLL

[WojTec]

Delphi-Quellcode:

library StringDLL;

uses
  SysUtils;

function Foonction(Data: PWideChar; Buffer: PWideChar; lenBuffer: Cardinal): Cardinal; stdcall;
var
  S: string;
begin
  S := 'foo' + Data;

  if Assigned(Buffer) then
    StrLCopy(Buffer, PWideChar(S), lenBuffer)
  ;

  Result := Length(S);
end;

exports
  Foonction;

begin
end.

Dynamic - working:

Delphi-Quellcode:

var
  hLib: THandle;
  func1: function(s: PChar; Buffer: PChar; lenBuffer: Integer): Integer; stdcall;
  len: Integer;
  Buffer: PChar;
begin
  Buffer := nil;
  hLib := LoadLibrary('StringDLL.dll');
  if hLib <> 0 then
  begin
    ListBox1.Items.Add('hlib: ' + IntToStr(hLib));
    @func1 := GetProcAddress(hLib, 'Foonction');
    if Assigned(func1) then
    begin
      ListBox1.Items.Add('@func1: ' + IntToStr(Integer(@func1)));
      len := func1('bar', nil, 0);
      ListBox1.Items.Add('len: ' + IntToStr(len));
      try
        GetMem(Buffer, len + 1);
        len := func1('bar', Buffer, len + 1);
        ListBox1.Items.Add(String(Buffer)+ ' [' + IntToStr(len) + ']');
      finally
        FreeMem(Buffer);
      end;
    end;
  end;
end;

Static - don't working:

Delphi-Quellcode:

function Foonction(Data: PWideChar; Buffer: PWideChar; lenBuffer: Cardinal): Cardinal; external 'StringDLL.dll';

var
  Buffer: PWideChar;
  BufferSize: DWORD;
begin
  BufferSize := Foonction('bar', nil, 0);
  ShowMessage(IntToStr(BufferSize));

  GetMem(Buffer, BufferSize + 1);
  try
    Foonction('bar', Buffer, BufferSize + 1);
    ShowMessage(Buffer);
  finally
    FreeMem(Buffer);
  end;
end;

Now I have identical sizes, what's wrong?