添加Lesson24

2025-09-17 19:59:36 +08:00
parent 1c4099eb8e
commit cb53f802bb
5 changed files with 131 additions and 0 deletions
@@ -57,6 +57,10 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Lesson23_面向对象相关
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Lesson23_面向对象相关-String练习", "Lesson23_面向对象相关-String练习\Lesson23_面向对象相关-String练习.csproj", "{E35D8933-50D7-496A-8E4C-06DDD1CC0878}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Lesson24_面向对象相关-StringBuilder", "Lesson24_面向对象相关-StringBuilder\Lesson24_面向对象相关-StringBuilder.csproj", "{25CCA649-1258-41DA-A5C1-B0C3DE89E2B6}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Lesson24_面向对象相关-StringBuilder练习", "Lesson24_面向对象相关-StringBuilder练习\Lesson24_面向对象相关-StringBuilder练习.csproj", "{4FFD2030-9A14-4F59-A7B8-D218C551E489}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -171,6 +175,14 @@ Global
 		{E35D8933-50D7-496A-8E4C-06DDD1CC0878}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{E35D8933-50D7-496A-8E4C-06DDD1CC0878}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{E35D8933-50D7-496A-8E4C-06DDD1CC0878}.Release|Any CPU.Build.0 = Release|Any CPU
+		{25CCA649-1258-41DA-A5C1-B0C3DE89E2B6}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{25CCA649-1258-41DA-A5C1-B0C3DE89E2B6}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{25CCA649-1258-41DA-A5C1-B0C3DE89E2B6}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{25CCA649-1258-41DA-A5C1-B0C3DE89E2B6}.Release|Any CPU.Build.0 = Release|Any CPU
+		{4FFD2030-9A14-4F59-A7B8-D218C551E489}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{4FFD2030-9A14-4F59-A7B8-D218C551E489}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{4FFD2030-9A14-4F59-A7B8-D218C551E489}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{4FFD2030-9A14-4F59-A7B8-D218C551E489}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -0,0 +1,11 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <RootNamespace>Lesson24_面向对象相关_StringBuilder</RootNamespace>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>
@@ -0,0 +1,71 @@
+using System.Text;
+
+namespace Lesson24_面向对象相关_StringBuilder
+{
+    internal class Program
+    {
+        static void Main(string[] args)
+        {
+            #region 知识回归
+            //string是一个比较特殊的引用类型
+            //每次赋值或修改，都会创建一个新的堆内存
+            //如果频繁修改字符串，会产生大量垃圾对象，影响性能
+            #endregion
+
+            #region 知识点 StringBuilder
+            //C#提供的一个用于处理字符串的公共类
+            //主要解决的问题是：
+            //修改字符串而不创建新的对象，需要频繁修改和拼接字符串可以使用他，可以提升性能
+            //使用前 需要引用命名空间
+            #endregion
+
+            #region 初始化 直接指明内容
+            StringBuilder str = new StringBuilder("Hello");//初始化时可以指定容量 eg:设置100的容量StringBuilder str = new StringBuilder("Hello",100);
+            Console.WriteLine(str);
+            #endregion
+
+            #region 容量
+            //StringBuilder存在一个容量的问题，每次往里添加内容时，如果超过了容量，就会自动扩容
+            //获得容量
+            Console.WriteLine(str.Capacity);
+            //获得字符长度
+            #endregion
+
+            #region 增删查改
+            //增 Append
+            str.Append(",World");
+            Console.WriteLine(str);
+            //增 AppendFormat
+            str.AppendFormat("! I am {0}, age {1}", "Tom", 20);
+            Console.WriteLine(str);
+            //删 Remove
+            str.Remove(5, 24);//从索引5开始删除6个字符
+            Console.WriteLine(str);
+            //查 ToString
+            Console.WriteLine(str.ToString());
+            //改 Replace
+            str[0] = 'h';//通过索引修改单个字符 
+            Console.WriteLine(str);
+            str.Replace("hello", "HELLO");//通过Replace修改字符串
+            Console.WriteLine(str);
+            //插 Insert
+            str.Insert(5, ", C#");//在索引5处插入字符串
+            Console.WriteLine(str);
+            //清空 Clear
+            str.Clear();
+            Console.WriteLine(str);
+            
+            //stringbuilder的其他方法
+            //Equals
+            if(str.Equals("hello"))
+            {
+                Console.WriteLine("相等");
+            }
+            else
+            {
+                Console.WriteLine("不相等");
+            }
+            #endregion
+        }
+    }
+}
@@ -0,0 +1,11 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <RootNamespace>Lesson24_面向对象相关_StringBuilder练习</RootNamespace>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>
@@ -0,0 +1,26 @@
+namespace Lesson24_面向对象相关_StringBuilder练习
+{
+    internal class Program
+    {
+        static void Main(string[] args)
+        {
+            #region 练习
+            //1.请描述String和StringBuilder的区别
+            //string比stringbuilder更容易产生垃圾 频繁修改会产生大量垃圾对象，影响性能
+            //string比stringbuilder更加灵活 方法更多
+            //如何选择string和stringbuilder
+            //需要频繁修改时，使用stringbuilder
+            //不需要频繁修改时或需要一些方法来处理麻烦的逻辑时，使用string
+
+
+            //2.如何优化内存
+            //两个方面：
+            //如何节约
+            //如何减少GC（垃圾回收）
+            //少new对象就少产生垃圾
+            //合理使用static
+            //合理使用string和stringbuilder
+            #endregion
+        }
+    }
+}