MFC获取时间差

CTime t1,t2;
CString startTimeStr,endTimeStr;
void CCycleTimeDlg::OnBnClickedBtnStart()
{
t1 = CTime::GetCurrentTime();
startTimeStr.Format("%02d:%02d:%02d",t1.GetHour(),t1.GetMinute(), t1.GetSecond());
}

void CCycleTimeDlg::OnBnClickedBtnEnd()
{
t2 = CTime::GetCurrentTime();
endTimeStr.Format("%02d:%02d:%02d",t2.GetHour(),t2.GetMinute(), t2.GetSecond());

CTimeSpan a = t2-t1;
int delay = a.GetMinutes()*60 + a.GetSeconds();

CString  CycleTime;
CycleTime.Format("%d",delay);

MessageBox(_T(CycleTime));

}

DWORD endTime;
CTime times=CTime::GetCurrentTime();
int curth,curtm,edh,edm;
curth = times.GetHour();
curtm = times.GetMinute();
edh = GetDlgItemInt(IDC_ED_HOUR);
edm = GetDlgItemInt(IDC_ED_MINT);
if (curth >= edh)
{
	if (curtm >= edm)
	{
		MySystemShutdown();
	}
}