时间比较方法DateTime.Compare

格式：DateTime.Compare(datetime1, datetime2)

参数为时间格式，为第一个参数比较第二个参数，返回小于0的值，等于0或大于0的值。

实例:

 string st1 = "12:13";
 string st2 = "14:13";
 DateTime t1 = Convert.ToDateTime(st1);
 Console.WriteLine(t1);  //20186/6 下午 12:12:00
 DateTime t2 = Convert.ToDateTime(st2);
 Console.WriteLine(t2);  //20186/6 下午 02:14:00
 DateTime t3 = DateTime.Now;
 Console.WriteLine(t3);
 if (DateTime.Compare(t1, t2) > ) Console.WriteLine(st1+">"+st2);
 else if (DateTime.Compare(t1, t2) == ) Console.WriteLine(st1+"="+st2);
 else Console.WriteLine(st1+"<"+st2); if (DateTime.Compare(t1, t3) > ) Console.WriteLine("\r\n"+st1 + ">" + t3.ToString());
 else if (DateTime.Compare(t1, t3) == ) Console.WriteLine("\r\n" + st1 + "=" + t3.ToString());
 else Console.WriteLine("\r\n" + st1 + "<" + t3.ToString());