How To Get Windows Uptime

function UpTime: string;
const
ticksperday : integer = 1000 * 60 * 60 * 24;
ticksperhour : integer = 1000 * 60 * 60;
ticksperminute : integer = 1000 * 60;
tickspersecond : integer = 1000;

var
 t : longword;
 d, h, m, s : integer;

begin
 t := GetTickCount;

 d := t div ticksperday;
 dec(t, d * ticksperday);

 h := t div ticksperhour;
 dec(t, h * ticksperhour);

 m := t div ticksperminute;
 dec(t, m * ticksperminute);

 s := t div tickspersecond;

 Result := 'Uptime: '+IntToStr(d)+ ' Days '+IntToStr(h)+' Hours '+IntToStr(m)+' Minutes '+IntToStr(s)+' Seconds';
end;


procedure TForm1.Button1Click(Sender: TObject);
begin
  label1.Caption:=UpTime;
end;