添加Lesson6

C#进阶/Lesson6_泛型约束练习/Lesson6_泛型约束练习.csproj

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

C#进阶/Lesson6_泛型约束练习/Program.cs

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+using System;
+
+namespace Lesson6_泛型约束练习
+{
+    #region 单例模式基类
+    class Test
+    {
+        private static Test instance = new Test();
+        public int value = 10;
+        public static Test Instance
+        {
+            get
+            {
+                return instance;
+            }
+        }
+        private Test() { }
+    }
+
+    class SingleBase<T> where T : new()
+    {
+        private static T instance = new T();
+        public static T Instance
+        {
+            get
+            {
+                return instance;
+            }
+        }
+    }
+
+    class GameManager : SingleBase<GameManager>
+    {
+        public GameManager()
+        {
+
+        }
+    }
+    #endregion
+
+    #region 利用泛型知识点，仿造ArrayList实现一个不确定数组类型的类 并 实现增删查改的方法
+    class ArrayList<T>
+    {
+        private T[] array;
+
+        private int count;
+        public ArrayList()
+        {
+            count = 0;
+            array = new T[16];
+        }
+        public void Add(T value)
+        {
+            if (count >= array.Length)
+            {
+                T[] temp = new T[Capacity * 2];
+                for (int i = 0; i < Capacity; i++)
+                {
+                    temp[i] = array[i];
+                }
+                array = temp;
+            }
+            array[count] = value;
+            count++;
+        }
+
+        public void Remove(T value)
+        {
+            int index = -1;
+            for (int i = 0; i < count; i++)//小于实际数量不小于容量
+            {
+                if (array[i].Equals(value))//不能写成array[i] == value因为不是所有类型都重载
+                {
+                    index = i;
+                    break;
+                }
+            }
+            if (index != -1)
+            {
+                for (;index < Count - 1;index++)
+                {
+                    array[index] = array[index + 1];
+                }
+                array[Count - 1] = default(T);
+                count--;
+            }
+        }
+
+        public void RemoveAt(int index)
+        {
+            if (index < 0 || index >= count)
+            {
+                Console.WriteLine("索引不合法");
+                return;
+            }
+            for (; index < Count - 1; index++)
+            {
+                array[index] = array[index + 1];
+            }
+            array[Count - 1] = default(T);
+            count--;
+        }
+
+        public T this[int index]
+        {
+            get
+            {
+                if (index < 0 || index >= count)
+                {
+                    Console.WriteLine("索引不合法");
+                    return default(T);
+                }
+                return array[index];
+            }
+            set
+            {
+                if (index < 0 || index >= count)
+                {
+                    Console.WriteLine("索引不合法");
+                    return;
+                }
+                array[index] = value;
+            }
+        }
+        /// <summary>
+        /// 得容量和实际数量
+        /// </summary>
+        public int Capacity
+        {
+            get
+            {
+                return array.Length;
+            }
+        }
+        public int Count
+        {
+            get
+            {
+                return count;
+            }
+        }
+    }
+    #endregion
+    class Program
+    {
+        static void Main(string[] args)
+        {
+            ArrayList<int> array = new ArrayList<int>();
+            Console.WriteLine(array.Count);
+            Console.WriteLine(array.Capacity);
+            array.Add(1);
+            array.Add(2);
+            array.Add(3);
+            Console.WriteLine(array.Count);
+            Console.WriteLine(array.Capacity);
+            Console.WriteLine(array[1]);
+            Console.WriteLine(array[-1]);
+            Console.WriteLine(array[5]);
+            array.Remove(2);
+            Console.WriteLine(array.Count);
+            Console.WriteLine("/////////////////");
+            for (int i = 0; i < array.Count; i++)
+            {
+                Console.Write(array[i]);
+            }
+            Console.WriteLine();
+            Console.WriteLine("/////////////////");
+            array.RemoveAt(0);
+            for (int i = 0; i < array.Count; i++)
+            {
+                Console.Write(array[i]);
+            }
+            Console.WriteLine();
+            Console.WriteLine("/////////////////");
+            array[1] = 555;
+            for (int i = 0; i < array.Count; i++)
+            {
+                Console.Write(array[i]);
+            }
+        }
+    }
+}