Integer < > HEX

Integer to HEX :

procedure TForm1.Button1Click(Sender: TObject);
var
 str : string;
 b   : byte;
begin
 b := 15;
 str := SysUtils.IntToHex(b,2);
 Label1.Caption := str;
end;

HEX to Integer :

procedure TForm1.Button2Click(Sender: TObject);
var
 strHexVal : string;
 intVal   : integer;
begin
 strHexVal := '0F';
 intVal := StrToInt('$' + strHexVal);
 Label1.Caption := IntToStr(intVal);
end;