MSDN：DateTime.Compare
DateTime date1 = new DateTime(2009, 8, 1, 0, 0, 0);DateTime date2 = new DateTime(2009, 8, 1, 12, 0, 0);int result = DateTime.Compare(date1, date2);string relationship;if (result < 0) relationship = "is earlier than";else if (result == 0) relationship = "is the same time as"; else relationship = "is later than";Console.WriteLine("{0} {1} {2}", date1, relationship, date2);// The example displays the following output:// 8/1/2009 12:00:00 AM is earlier than 8/1/2009 12:00:00 PM
