delphi 取得开机时间 开机时间总长度（可精确到秒，分钟等）

procedure TForm1.Button1Click(Sender: TObject);
//GetTickCount函数可以得到从开以来所经过的毫秒数.再与当前时间相减就可以了!
var
StartTime:TDateTime;
begin
StartTime:=Now-GetTickCount/1000/60/60/24;
showmessage('本次开机时间为：'+DateTimeToStr(StartTime));

{uses DateUtils; SecondsBetween

也可用MinuteBetween,function YearsBetween(const ANow, AThen: TDateTime): Integer;
function MonthsBetween(const ANow, AThen: TDateTime): Integer;
function WeeksBetween(const ANow, AThen: TDateTime): Integer;
function DaysBetween(const ANow, AThen: TDateTime): Integer;
function HoursBetween(const ANow, AThen: TDateTime): Int64;
function MinutesBetween(const ANow, AThen: TDateTime): Int64;
function SecondsBetween(const ANow, AThen: TDateTime): Int64;
function MilliSecondsBetween(const ANow, AThen: TDateTime): Int64; }

showmessage('本次开机总时间长度为：'+inttostr(SecondsBetween(Now,StartTime))+'秒');
end;