function TFormMain.GetWeek: string;var  date:SYSTEMTIME;begin  GetLocalTime(date);  case date.wDayOfWeek of    0:Result:='星期天';    1:Result:='星期一';    2:Result:='星期二';    3:Result:='星期三';    4:Result:='星期四';    5:Result:='星期五';    6:Result:='星期六';  end;end;

 返回值为当天的星期几

function GetSubDateTime(S1, S2:string): string;var  T1, T2: TDateTime;  D, H, M, S: Integer;  Value: Int64;begin  T1 := StrToDateTime(S1);  T2 := StrToDateTime(S2);  Value := SecondsBetween(T1, T2);   //两个时间之间相差的秒数  D := Value div SecsPerDay;  H := Value mod SecsPerDay div SecsPerHour;  M := Value mod SecsPerDay mod SecsPerHour div SecsPerMin;  S := Value mod SecsPerDay mod SecsPerHour mod SecsPerMin;  result := Format('%2d天 %.2d:%.2d:%.2d',[D, H, M, S]); // 返回几天：几时：几分：几秒end;