1    /**//// <summary>
 2    /// 重新订票的接口
 3    /// </summary>
 4    internal interface IReBook
 5    {
 6        Ticket ReBook(String newTerminal, Int32 newDistance);
 7    }
 8
 9    internal struct Ticket:IReBook
10    {
11        private String _start, _terminal;//起点和终点
12        private Int32 _distance;//距离
13
14        public Ticket(string start, string terminal, Int32 distance)
15        {
16            _start = start;
17            _terminal = terminal;
18            _distance = distance;
19        }
20
21
22        /**//// <summary>
23        /// 重写System.ValueType的ToString方法
24        /// </summary>
25        public override String ToString()
26        {
27            return String.Format("From {0} To {1} , {2} km",
28                _start,
29                _terminal,
30                _distance);//在方法的内部，_distance被装箱
31        }
32
33        IReBook Members#region IReBook Members
34        /**//// <summary>
35        /// 重新订票
36        /// </summary>
37        /// <param name="newTerminal">新的终点站</param>
38        /// <param name="newDistance">到终点站的距离</param>
39      public Ticket ReBook(string newTerminal, int newDistance)
40        {
41            _terminal = newTerminal;
42            _distance = newDistance;
43            return this;
44        }
45
46        #endregion
47    }
48
49    public sealed class Program
50    {
51        public static void Main()
52        {
53            Ticket t = new Ticket("北京", "汉口", 1225);
54            //值类型实例t在这里第一次被装箱:Ticket-->Object-->override ToString
55            Console.WriteLine(t);
56
57            //显示的装箱
58            // Console.WriteLine(((Object)t).ToString());
59
60            t.ReBook("上海", 1400);
61            Console.WriteLine(t);
62
63            Object o = t;
64            Console.WriteLine(o);
65
66            Ticket t2 = ((Ticket)o).ReBook("广州", 2000);
67            Console.WriteLine(o);
68            Console.WriteLine(t2);
69
70            //t-->IReBook,被装箱
71            ((IReBook)t).ReBook("广州", 2000);
72            Console.WriteLine(t);
73
74            //o-->IReBook,无须装箱
75            ((IReBook)o).ReBook("广州", 2000);
76            Console.WriteLine(o);
77        }
78    }