1 using System; 2 using System.Collections.Generic; 3 using System.Linq; 4 using System.Text; 5  6 namespace OverrideTest 7 { 8     //抽象类 9    public abstract class PdaItem10     {11        public PdaItem(string name)12        {13            Name = name;14        }15        public virtual string Name { get; set; }16        public abstract string GetSummary();//纯虚函数，强制子类实现，他也实现了多态17     }18 }

 1 using System; 2 using System.Collections.Generic; 3 using System.Linq; 4 using System.Text; 5  6 namespace OverrideTest 7 { 8     class Contacts:PdaItem 9     {10         public Contacts(string name)//继承父类的构造函数11             : base(name)12         {13             Name = name;14         }15         public override string Name16         {17             get18             {19                 return FirstName + " " + LastName;  20             }21             set22             {23                 string[] names = value.Split(‘ ‘);24                 FirstName = names[0];25                 LastName = names[1];26             }27         }28         public string FirstName { get; set; }29         public string LastName { get; set; }30         public string Address { get; set; }31         public override string GetSummary()//强制重写32         {33             return string.Format("FirstName :{0}" + "LstName:{1}" + "Address:{2}", FirstName, LastName, Address);34         }35     }36 }

 1 using System; 2 using System.Collections.Generic; 3 using System.Linq; 4 using System.Text; 5  6 namespace OverrideTest 7 { 8     class Appointment:PdaItem 9     {10         public Appointment(string name):base(name)11         {12             Name = name;13         }14         public DateTime StartDateTime { get; set; }15         public DateTime EndDateTime { get; set; }16         public string Location { get; set; }17         public override string GetSummary()//强制重写18         {19             return string.Format("Subject:{0}" + Environment.NewLine20                 + "Start:{1}" + Environment.NewLine21                 + "End:{2}" + Environment.NewLine22                 + "Location:{3}",23                 Name, StartDateTime, EndDateTime, Location24                 );25         }26     }27 }

 1 PdaItem[] pda = new PdaItem[3]; 2  3             Contacts contacts = new Contacts("Tom Li"); 4             contacts.Address = "Chongwen Road NananZone Chongqing City China"; 5             pda[0] = contacts; 6  7             Appointment appointment = new Appointment("Tms Cli"); 8             appointment.StartDateTime = new DateTime(2014, 10, 10); 9             appointment.EndDateTime = new DateTime(2014, 10, 11);10             appointment.Location = "Chongqing Unibersity of Posts and Telecommunictions";11             pda[1] = appointment;12 13             contacts = new Contacts("another one");14             contacts.Address = "thrity-thress dormitory";15             pda[2] = contacts;16             List(pda);17         }18         public static void List(PdaItem[] items)19         {20             foreach (PdaItem item in items)21             {22                 Console.WriteLine("---------------------------");23                 Console.WriteLine(item.GetSummary());//虽然调用的都是基类的同一个函数，但是基类的三个对象分别指向了不同的子类，所以他们都选择了各自的继承链里面重写的最远的那个。24             }25         }