C# 比较时间大小

                            string s="2013/12/6 16:04:59"; //nvr时间

                           string sd = "2013-12-06 16:00:08";  //输入时间                     

                              DateTime dt1 = Convert.ToDateTime(s);                 

                             DateTime dt2 = Convert.ToDateTime(sd);            

                               if (DateTime.Compare(dt1, dt2) > 0)          

                         {                              

                                 MessageBox.Show("sd 小");

                                string ww= dt1.ToString("yyy-MM-dd HH:mm:ss");         

                              }                          

                         if (DateTime.Compare(dt1, dt2) < 0)                

                    {                             

                           MessageBox.Show("s 小");            

                    }