static void Main(string[] args)

         {

             string str = "1";

             string str2 = "2";

             int a=str2.CompareTo(str);      //str2与compareTo(参数str)比较。2大于1，返回值为1。

             Console.WriteLine(a.ToString());

             if (a<0)

             {

                 Console.WriteLine("true");

             }

             else 

             {

                 Console.WriteLine("wrong");

             }           

             Console.ReadKey();

         }