Get a user name

Use GetUserName for solving of this problem. For example:

procedure TForm1.Button1Click(Sender: TObject);
var
  StrUserName: PChar;
  Size: DWord;
begin
  Size:=250;
  GetMem(StrUserName, Size);
  GetUserName(StrUserName, Size);
  Label1.Caption:=StrPas(StrUserName);
  FreeMem(StrUserName);
end;