添加Lesson17

C#核心/C#核心.sln

@@ -31,6 +31,10 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Lesson16_继承-密封类",
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Lesson16_继承-密封类练习", "Lesson16_继承-密封类练习\Lesson16_继承-密封类练习.csproj", "{673FABF2-99A7-4E63-B1F6-37AB53B6EC85}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Lesson17_多态-vob", "Lesson17_多态-vob\Lesson17_多态-vob.csproj", "{9B334A2E-3B5C-49AC-B1E8-2CE2FDC04158}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Lesson17_多态-vob练习", "Lesson17_多态-vob练习\Lesson17_多态-vob练习.csproj", "{B9598C23-6AD4-44FB-B16B-6A0A80B8D9CD}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -93,6 +97,14 @@ Global
 		{673FABF2-99A7-4E63-B1F6-37AB53B6EC85}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{673FABF2-99A7-4E63-B1F6-37AB53B6EC85}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{673FABF2-99A7-4E63-B1F6-37AB53B6EC85}.Release|Any CPU.Build.0 = Release|Any CPU
+		{9B334A2E-3B5C-49AC-B1E8-2CE2FDC04158}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{9B334A2E-3B5C-49AC-B1E8-2CE2FDC04158}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{9B334A2E-3B5C-49AC-B1E8-2CE2FDC04158}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{9B334A2E-3B5C-49AC-B1E8-2CE2FDC04158}.Release|Any CPU.Build.0 = Release|Any CPU
+		{B9598C23-6AD4-44FB-B16B-6A0A80B8D9CD}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{B9598C23-6AD4-44FB-B16B-6A0A80B8D9CD}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{B9598C23-6AD4-44FB-B16B-6A0A80B8D9CD}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{B9598C23-6AD4-44FB-B16B-6A0A80B8D9CD}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE

C#核心/Lesson14_继承-继承中的构造函数/Program.cs

@@ -55,7 +55,8 @@
     //父类的父类的构造->...父类构造->...->子类构造
     class GameObject
     {
-        public GameObject() {
+        public GameObject() 
+        {
             Console.WriteLine("gameobject的构造函数");
         }
     }

C#核心/Lesson17_多态-vob/Lesson17_多态-vob.csproj

@@ -0,0 +1,11 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <RootNamespace>Lesson17_多态_vob</RootNamespace>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

C#核心/Lesson17_多态-vob/Program.cs

@@ -0,0 +1,134 @@
+namespace Lesson17_多态_vob
+{
+    #region 知识回顾
+
+    #region 封装——用程序语言来形容对象
+    class 类名
+    {
+        #region 特征——成员变量
+        #endregion
+
+        #region 行为——成员方法
+        #endregion
+
+        #region 初始化调用——构造函数
+        #endregion
+
+        #region 释放时调用——析构函数
+        #endregion
+
+        #region 保护成员变量——成员属性
+        #endregion
+
+        #region 像数组一样使用——索引器
+        #endregion
+
+        #region 类名点出直接使用——静态成员
+        #endregion
+
+        #region 自定义对象可计算——运算符重载
+        #endregion
+    }
+
+    #region 静态类和静态构造函数
+    #endregion
+
+    #region 拓展方法
+    #endregion
+
+    #endregion
+
+    #region 继承——复用封装对象的代码：儿子继承父亲，复用现成代码
+    #endregion
+
+    #endregion
+
+    #region 知识点一 多态的概念
+    // 多态按字面意思就是“多种状态”
+    // 让继承同一父类的子类们 在执行相同方法时有不同的表现（状态）
+    // 主要目的
+    // 同一父类的对象 执行相同行为（方法）有不同的表现
+    // 解决的问题
+    // 让同一个对象有位移行为的特征
+    #endregion
+
+    #region 知识点二 解决的问题
+    class Father
+    {
+        public void Speak()
+        {
+            Console.WriteLine("Father Speak");
+        }
+    }
+    class Son : Father
+    {
+        public void Speak()
+        {
+            Console.WriteLine("Son Speak");
+        }
+    }
+    #endregion
+
+    #region 知识点三 多态的实现
+    //我们目前已经学过的多态
+    //编译时多态——函数重载，开始就写好的
+
+    //我们将学习的：
+    //运行时多态（vob、抽象函数、接口）
+    //我们今天学习 vob
+    //v: virtual(虚函数)
+    //o: override(重写)
+    //b: base(父类)
+
+
+
+    class GameObject
+    {
+        public string name;
+        public GameObject(string name)
+        {
+            this.name = name;
+        }
+
+        public virtual void Atk()//虚函数
+        {
+            Console.WriteLine("游戏对象攻击");
+        }
+    }
+    class Player : GameObject
+    {
+        public Player(string name):base(name) 
+        {
+         
+        }
+        //代表着重写虚函数
+        public override void Atk()
+        {
+            //base来保留父类的函数
+            base.Atk();//执行父类(base)的Atk方法
+            Console.WriteLine("玩家对象攻击");
+        }
+    }
+    #endregion
+    internal class Program
+    {
+        static void Main(string[] args)
+        {
+            Console.WriteLine("Hello, World!");
+            #region 解决的问题
+            Father f = new Son();
+            f.Speak();
+
+            (f as Son).Speak();
+            #endregion
+
+            #region 多态的使用
+            GameObject p = new Player("123");
+            p.Atk();//虽然是父类对象装载的p，但是p是他的子类player类型的
+                    //如果不用override来重写，那么调用的atk将会是父类的atk
+                    //既然有了虚函数和重写那么调用的就是子类的atk
+
+            #endregion
+        }
+    }
+}

C#核心/Lesson17_多态-vob练习/Lesson17_多态-vob练习.csproj

@@ -0,0 +1,11 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <RootNamespace>Lesson17_多态_vob练习</RootNamespace>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

C#核心/Lesson17_多态-vob练习/Program.cs

@@ -0,0 +1,154 @@
+using System.Threading.Channels;
+
+namespace Lesson17_多态_vob练习
+{
+    #region 鸭子题
+    class Duck
+    {
+        public virtual void Speak()
+        {
+            Console.WriteLine("嘎嘎叫");
+        }
+    }
+    class WoodDuck : Duck
+    {
+        public override void Speak()
+        {
+            Console.WriteLine("吱吱叫");
+        }
+
+    }
+    class RubberDuck : Duck
+    {
+        public override void Speak()
+        {
+            Console.WriteLine("叽叽叫");
+        }
+    }
+    #endregion
+
+    #region 打卡题
+    class Staff
+    {
+        public virtual void Clockin() 
+        {
+            Console.WriteLine("员工9点打卡");
+        }
+    }
+    class Boss: Staff
+    {
+        public override void Clockin()
+        {
+            Console.WriteLine("老板11点打卡");
+        }
+
+    }
+    class Programer : Staff
+    {
+        public override void Clockin()
+        {
+            Console.WriteLine("程序员无需打卡");
+        }
+    }
+    #endregion
+
+    #region 计算题
+    class Graph
+    {
+        public virtual void Perimeter()
+        {
+            Console.WriteLine("未初始化图形无法计算");
+        }
+        public virtual void Area()
+        {
+            Console.WriteLine("未初始化图形无法计算");
+        }
+    }
+    class Rectangle : Graph
+    {
+        public int x, y;
+        public Rectangle(int x, int y)
+        {
+            this.x = x;
+            this.y = y;
+        }
+        public override void Perimeter()
+        {
+            Console.WriteLine("矩形周长为{0}", (x + y) * 2);
+        }
+        public override void Area()
+        {
+            Console.WriteLine("矩形面积为{0}", x * y);
+        }
+    }
+    class Square : Graph
+    {
+        public int x;
+        public Square(int x)
+        {
+            this.x = x;
+        }
+
+        public override void Perimeter()
+        {
+            Console.WriteLine("方的周长为{0}", x * 4);
+        }
+        public override void Area()
+        {
+            Console.WriteLine("方的面积为{0}", x * x);
+        }
+    }
+    class Round : Graph
+    {
+        public double PI = 3.1415926;
+        int r;
+        public Round(int r)
+        {
+            this.r = r;
+        }
+        public override void Perimeter()
+        {
+            double perimeter = 2 * PI * r;
+            Console.WriteLine("圆的周长{0}",perimeter);
+        }
+        public override void Area()
+        {
+            double areas = PI * r * r;
+            Console.WriteLine("圆的面积{0}",areas);
+        }
+    }
+
+    #endregion
+
+    internal class Program
+    {
+        static void Main(string[] args)
+        {
+            Console.WriteLine("Hello, World!");
+            Duck realDuck = new Duck();
+            realDuck.Speak();
+            Duck woodDuck = new WoodDuck();
+            woodDuck.Speak();
+            Duck rubberDuck = new RubberDuck();
+            rubberDuck.Speak();
+
+            Programer p = new Programer();
+            p.Clockin();
+            Boss b = new Boss();
+            b.Clockin();
+            Staff s = new Staff();
+            s.Clockin();
+             
+            Graph rectangle = new Rectangle(2,3);
+            rectangle.Perimeter();
+            rectangle.Area();
+            Graph square = new Square(2);
+            square.Perimeter();
+            square.Area();
+            Graph round = new Round(3);
+            round.Perimeter();
+            round.Area();
+
+        }
+    }
+}