struct aaa a;

using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;namespace ConsoleApplication5
 {
     struct aaa
     {
         public int a;
         public override String ToString()
         {
             return String.Format("My data is: {0}", a);
         }
     }    class Program
     {
         static void Main(string[] args)
         {
             aaa a/*=new aaa()*/;
             a.a= 100;
             Console.WriteLine("{0}", a);
 My data is: 100
 请按任意键继续. . .
         }
     }
 }