添加Lesson4

C#进阶/C#进阶.sln

@@ -17,6 +17,10 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Lesson3_Queue", "Lesson3_Qu
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Lesson3_Queue练习题", "Lesson3_Queue练习题\Lesson3_Queue练习题.csproj", "{77AE0EA5-FD54-46A0-A708-A2B38ABEE26D}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Lesson4_Hashtable", "Lesson4_Hashtable\Lesson4_Hashtable.csproj", "{C703B2F8-529B-46E0-8D8E-07750A812966}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Lesson4_Hashtable练习题", "Lesson4_Hashtable练习题\Lesson4_Hashtable练习题.csproj", "{962C9536-7CD7-4F5A-9D1E-1DCF986953D4}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -51,6 +55,14 @@ Global
 		{77AE0EA5-FD54-46A0-A708-A2B38ABEE26D}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{77AE0EA5-FD54-46A0-A708-A2B38ABEE26D}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{77AE0EA5-FD54-46A0-A708-A2B38ABEE26D}.Release|Any CPU.Build.0 = Release|Any CPU
+		{C703B2F8-529B-46E0-8D8E-07750A812966}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{C703B2F8-529B-46E0-8D8E-07750A812966}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{C703B2F8-529B-46E0-8D8E-07750A812966}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{C703B2F8-529B-46E0-8D8E-07750A812966}.Release|Any CPU.Build.0 = Release|Any CPU
+		{962C9536-7CD7-4F5A-9D1E-1DCF986953D4}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{962C9536-7CD7-4F5A-9D1E-1DCF986953D4}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{962C9536-7CD7-4F5A-9D1E-1DCF986953D4}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{962C9536-7CD7-4F5A-9D1E-1DCF986953D4}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE

C#进阶/Lesson4_Hashtable/Lesson4_Hashtable.csproj

@@ -0,0 +1,10 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

C#进阶/Lesson4_Hashtable/Program.cs

@@ -0,0 +1,109 @@
+using System.Collections;
+
+namespace Lesson4_Hashtable
+{
+    internal class Program
+    {
+        static void Main(string[] args)
+        {
+            #region 知识点一 Hashtable的本质
+            //Hashtable（又称散列表）是基于键的哈希代码组织起来的键/值对的集合。
+            //它的主要作用是提高数据查询的效率
+            //使用键来快速查找对应的值，而不需要遍历整个集合。
+            #endregion
+
+            #region 知识点二 声明
+            //需要引用system.collections命名空间
+            Hashtable hashtable = new Hashtable();
+            #endregion
+
+            #region 知识点三 增删查改
+            //只能通过键来操作值
+
+            //增
+            hashtable.Add("001", "张三");
+            //              ↑键    ↑值
+            hashtable.Add("002", "李四");
+            hashtable.Add(true, false);
+            hashtable.Add(false, false);
+            //注意：不能出现相同的键
+
+
+            //删
+            //1.只能通过键来删除
+            hashtable.Remove("001");
+            //2.删除不存在的键不会报错也不会有任何反应
+            hashtable.Remove("003");
+            //3.清空
+            hashtable.Clear();
+            hashtable.Add(1, "张三");
+            hashtable.Add(2, "李四");
+            hashtable.Add(3, false);
+            hashtable.Add(true, false);
+
+
+            //查
+            //1.通过键来查找值，找不到返回null
+            Console.WriteLine(hashtable[1]);//找键值为1的值
+            Console.WriteLine(hashtable[4]);//不存在，返回null
+            Console.WriteLine(hashtable[true]);//找键值为true的值
+            //2.查看是否存在
+            //根据键检测
+            if(hashtable.ContainsKey(2))
+            {
+                Console.WriteLine("存在键为2的元素");
+            }
+            if(hashtable.ContainsKey(4))
+            {
+                Console.WriteLine("存在键为4的元素");
+            }
+            //根据值检测
+            if(hashtable.ContainsValue("李四"))
+            {
+                Console.WriteLine("存在值为李四的元素");
+            }
+
+
+            //改
+            hashtable[1] = "王五";//修改键为1的值
+            #endregion
+
+            #region 知识点四 遍历
+            //1.对数
+            Console.WriteLine(hashtable.Count);
+
+            //2.遍历所有键
+            foreach (object item in hashtable.Keys)
+            {
+                Console.WriteLine("键"+item);
+                Console.WriteLine("值"+hashtable[item]);
+            }
+
+            //3.遍历所有值
+            foreach (object item in hashtable.Values)
+            {
+                Console.WriteLine("值"+item);
+            }
+
+            //3.键值对一起遍历
+            foreach (DictionaryEntry item in hashtable)
+            {
+                Console.WriteLine("键值"+item.Key+item.Value); 
+            }
+
+            //4.迭代器遍历法
+            IDictionaryEnumerator myEnumerator = hashtable.GetEnumerator();
+            bool flag = myEnumerator.MoveNext();
+            while (flag)
+            {
+                Console.WriteLine("键值" + myEnumerator.Key + myEnumerator.Value);
+                flag = myEnumerator.MoveNext();
+            }
+            #endregion
+
+            #region 知识点五 装箱拆箱
+            //一样的
+            #endregion
+        }
+    }
+}

C#进阶/Lesson4_Hashtable练习题/Lesson4_Hashtable练习题.csproj

@@ -0,0 +1,10 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

C#进阶/Lesson4_Hashtable练习题/Program.cs

@@ -0,0 +1,70 @@
+using System;
+using System.Collections;
+using System.Security.Cryptography.X509Certificates;
+using System.Threading;
+namespace Lesson4_Hashtable练习题
+{
+    //因为一般管理器都是唯一的，所以做成单例模式的对象
+    class MonsterMgr
+    {
+        private static MonsterMgr instance = new MonsterMgr();
+        private Hashtable monstersTable = new Hashtable();
+        private MonsterMgr()
+        {
+
+        }
+        public static MonsterMgr Instance
+        {
+            get
+            {
+                return instance;
+            }
+        }
+        
+        private int monsterID = 0;
+
+        public void AddMonster()
+        {
+
+            Monster monster = new Monster(monsterID);
+            Console.WriteLine("创建了怪物"+monsterID);
+            monsterID++;
+            monstersTable.Add(monster.id, monster);
+        }
+
+        public void DeleteMonster(int monsterID)
+        {
+            if (monstersTable.ContainsKey(monsterID))
+            {
+                (monstersTable[monsterID] as Monster).Dead();
+                monstersTable.Remove(monsterID);
+            }
+        }
+    }
+    class Monster
+    {
+        public int id;
+        public Monster(int id)
+        {
+            this.id = id;
+        }
+        public void Dead()
+        {
+            Console.WriteLine("怪物"+id+"死亡");
+        }
+    }
+    class Program
+    {
+        static void Main(string[] args)
+        {
+            MonsterMgr.Instance.AddMonster();
+            MonsterMgr.Instance.AddMonster();
+            MonsterMgr.Instance.AddMonster();
+            MonsterMgr.Instance.AddMonster();
+            MonsterMgr.Instance.AddMonster();
+            MonsterMgr.Instance.DeleteMonster(0);
+            MonsterMgr.Instance.DeleteMonster(3);
+
+        }
+    }
+}