代码：

1 using System;  2 using System.Collections.Generic;  3 using System.Linq;  4 using System.Text;  5 using System.Threading.Tasks;  6   7 namespace 接口  8 {  9     /// 
 10     /// 接口：定义一个统一的标准 11     /// 声明接口，接口中，只包含成员的生命，不包含任何的代码实现。 12     /// 接口成员总是公有的，不添加也不需要添加public，也不能声明虚方法和虚静态方法 13     /// 
 14     interface IBankAccount 15     { 16         //方法 17         void PayIn(decimal amount); 18  19         //方法 20         bool WithShowMyself(decimal amount); 21  22         //属性 23         decimal Balance { get; } 24     } 25  26     /// 
 27     /// 继承自IBankAccount的接口 28     /// 
 29     interface ITransferBankAccount : IBankAccount 30     { 31         //转账          ：转入的目的地             ：转入金额 32         bool TransferTo(IBankAccount destination, decimal amount); 33     } 34  35     class SaveAcount : IBankAccount 36     { 37         //私有变量 38         private decimal banlance; 39  40         //存款 41         public void PayIn(decimal amount) 42         { 43             banlance += amount; 44         } 45  46         //取款 47         public bool WithShowMyself(decimal amount) 48         { 49             if (banlance >= amount) 50             { 51                 banlance -= amount; 52                 return true; 53             } 54             else 55             { 56                 Console.WriteLine("余额不足！"); 57                 return false; 58             } 59         } 60  61         //账户余额 62         public decimal Balance 63         { 64             get 65             { 66                 return banlance; 67             } 68         } 69     } 70  71     //实现接口的类的相应成员必须添加public修饰 72     class ITransferAccount : ITransferBankAccount 73     { 74         //私有变量 75         private decimal banlance; 76  77         //存款 78         public void PayIn(decimal amount) 79         { 80             banlance += amount; 81         } 82  83         //取款 84         public bool WithShowMyself(decimal amount) 85         { 86             if (banlance >= amount) 87             { 88                 banlance -= amount; 89                 return true; 90             } 91             else 92             { 93                 Console.WriteLine("余额不足！"); 94                 return false; 95             } 96         } 97  98         //账户余额 99         public decimal Balance100         {101             get102             {103                 return banlance;104             }105         }106 107         //转账108         public bool TransferTo(IBankAccount destination, decimal amount)109         {110             bool result = WithShowMyself(amount);111 112             if (result == true)113             {114                 destination.PayIn(amount);115             }116 117             return result;118         }119     }120 121 122     class Program123     {124         static void Main(string[] args)125         {126             IBankAccount MyAccount = new SaveAcount();127 128             ITransferAccount YourAccount = new ITransferAccount();129 130             MyAccount.PayIn(10000);131 132             YourAccount.PayIn(30000);133 134             YourAccount.TransferTo(MyAccount, 5000);135 136             Console.WriteLine(MyAccount.Balance);//15000137             Console.WriteLine();138             Console.WriteLine(YourAccount.Balance);//25000139 140             Console.ReadKey();141         }142     }143 }