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data/1..NET初阶/1.入门/5..NET Standard概述/StandardQuery.json

+{
+    "type": "code_options",
+    "author": "huanhuilong",
+    "source": "StandardQuery.md"
+}
\ No newline at end of file

data/1..NET初阶/1.入门/5..NET Standard概述/StandardQuery.md

+# .NET 规范实现情况的查询
+
+.NET Standard 是针对多个 .NET 实现推出的一套正式的 .NET API 规范。
+
+请编写一段代码，支持功能：**查询支持某个 .NET Standard 版本的所有.NET 实现的最低版本**。
+
+执行运行命令`dotnet new console --output StandardQuery`创建测试项目，添加测试代码如下：
+
+```csharp
+// 下面的C#列表，表示.NET Standard的版本号列表
+var dotnetStandard = new List<string>(){
+    "1.0", "1.1", "1.2", "1.3", "1.4", "1.5", "1.6", "2.0", "2.1"
+};
+
+// 而下面的C#字典，表示了.NET 每种实现支持上述对应.NET Standard 规范的最低版本：
+var dotnetImplements = new Dictionary<string, List<string>>(){
+    [".NET 和.NET Core"]=new List<string>(){"1.0", "1.0", "1.0", "1.0", "1.0", "1.0", "1.0", "2.0", "3.0"},
+    [".NET Framework"]=new List<string>(){"1", "4.5", "4.5", "4.5.1", "4.6", "4.6.1", "4.6.1^2", "4.6.1", "2", "4.6.1^2", "N/A3"},
+    ["Mono"]=new List<string>(){"4.6", "4.6", "4.6", "4.6", "4.6", "4.6", "4.6", "5.4", "6.4"},
+    ["Xamarin.iOS"]=new List<string>(){"10.0", "10.0", "10.0", "10.0", "10.0", "10.0", "10.0", "10.14", "12.16"},
+    ["Xamarin.Mac"]=new List<string>(){"3.0", "3.0", "3.0", "3.0", "3.0", "3.0", "3.0", "3.8", "5.16"},
+    ["Xamarin.Android"]=new List<string>(){"7.0", "7.0", "7.0", "7.0", "7.0", "7.0", "7.0", "8.0", "10.0"},
+    ["通用 Windows 平台"]=new List<string>(){"10.0", "10.0", "10.0", "10.0", "10.0", "10.0.16299", "10.0.16299", "10.0.16299", "待定"},
+    ["Unity"]=new List<string>(){"2018/1", "2018/1", "2018/1", "2018/1", "2018/1", "2018/1", "2018/1", "2018/1", "2021.2"}
+};
+
+var dotnetStandardQuery = new Dictionary<string, List<string>>();
+
+//TODO(You): 请在此实现代码
+
+Console.WriteLine("以下各种.NET的实现，支持了 .NET Standard 2.1的最低版本是：");
+Console.WriteLine("====");
+foreach(var lowlowerSupportImplementVersion in dotnetStandardQuery["2.1"]){
+    Console.WriteLine("* "+lowlowerSupportImplementVersion);
+}
+```
+
+执行运行命令`dotnet run --project StandardQuery` 后输出：
+
+```bash
+以下各种.NET的实现，支持了 .NET Standard 2.1的最低版本是：
+====
+* .NET 和.NET Core，版本：3.0
+* .NET Framework，版本：2
+* Mono，版本：6.4
+* Xamarin.iOS，版本：12.16
+* Xamarin.Mac，版本：5.16
+* Xamarin.Android，版本：10.0
+* 通用 Windows 平台，版本：待定
+* Unity，版本：2021.2
+```
+
+以下正确的实现代码是？
+
+## 答案
+
+```csharp
+int i=0;
+foreach(var standardVersion in dotnetStandard){
+    var lowerSupportImplementVersions = new List<String>();
+    foreach(var dotnetImplement in dotnetImplements){
+        lowerSupportImplementVersions.Add(dotnetImplement.Key+"，版本："+dotnetImplement.Value[i]);
+    }
+    dotnetStandardQuery.Add(standardVersion, lowerSupportImplementVersions);
+    i++;
+}
+```
+
+## 选项
+
+### 取值不对
+
+```csharp
+int i=0;
+foreach(var standardVersion in dotnetStandard){
+    var lowerSupportImplementVersions = new List<String>();
+    foreach(var dotnetImplement in dotnetImplements){
+        lowerSupportImplementVersions.Add(dotnetImplement.Key+"，版本："+dotnetImplement);
+    }
+    dotnetStandardQuery.Add(standardVersion, lowerSupportImplementVersions);
+    i++;
+}
+```
+
+### 少了分号
+
+```cshapp
+int i=0
+foreach(var standardVersion in dotnetStandard){
+    var lowerSupportImplementVersions = new List<String>()
+    foreach(var dotnetImplement in dotnetImplements){
+        lowerSupportImplementVersions.Add(dotnetImplement.Key+"，版本："+dotnetImplement.Value[i])
+    }
+    dotnetStandardQuery.Add(standardVersion, lowerSupportImplementVersions)
+    i++
+}
+```
+
+### 列表初始化不对
+
+```csharp
+int i=0;
+foreach(var standardVersion in dotnetStandard){
+    var lowerSupportImplementVersions = [];
+    foreach(var dotnetImplement in dotnetImplements){
+        lowerSupportImplementVersions.Add(dotnetImplement.Key+"，版本："+dotnetImplement.Value[i]);
+    }
+    dotnetStandardQuery.Add(standardVersion, lowerSupportImplementVersions);
+    i++;
+}
+```

data/1..NET初阶/1.入门/5..NET Standard概述/StandardQuery/Program.cs

+// See https://aka.ms/new-console-template for more information
+
+
+var dotnetStandard = new List<string>(){
+    "1.0", "1.1", "1.2", "1.3", "1.4", "1.5", "1.6", "2.0", "2.1"
+};
+
+
+var dotnetImplements = new Dictionary<string, List<string>>(){
+    [".NET 和.NET Core"]=new List<string>(){"1.0", "1.0", "1.0", "1.0", "1.0", "1.0", "1.0", "2.0", "3.0"},
+    [".NET Framework"]=new List<string>(){"1", "4.5", "4.5", "4.5.1", "4.6", "4.6.1", "4.6.1^2", "4.6.1", "2", "4.6.1^2", "N/A3"},
+    ["Mono"]=new List<string>(){"4.6", "4.6", "4.6", "4.6", "4.6", "4.6", "4.6", "5.4", "6.4"},
+    ["Xamarin.iOS"]=new List<string>(){"10.0", "10.0", "10.0", "10.0", "10.0", "10.0", "10.0", "10.14", "12.16"},
+    ["Xamarin.Mac"]=new List<string>(){"3.0", "3.0", "3.0", "3.0", "3.0", "3.0", "3.0", "3.8", "5.16"},
+    ["Xamarin.Android"]=new List<string>(){"7.0", "7.0", "7.0", "7.0", "7.0", "7.0", "7.0", "8.0", "10.0"},
+    ["通用 Windows 平台"]=new List<string>(){"10.0", "10.0", "10.0", "10.0", "10.0", "10.0.16299", "10.0.16299", "10.0.16299", "待定"},
+    ["Unity"]=new List<string>(){"2018/1", "2018/1", "2018/1", "2018/1", "2018/1", "2018/1", "2018/1", "2018/1", "2021.2"}
+};
+
+var dotnetStandardQuery = new Dictionary<string, List<string>>();
+int i=0;
+foreach(var standardVersion in dotnetStandard){
+    var lowerSupportImplementVersions = new List<String>();
+    foreach(var dotnetImplement in dotnetImplements){
+        lowerSupportImplementVersions.Add(dotnetImplement.Key+"，版本："+dotnetImplement.Value[i]);
+    }
+    dotnetStandardQuery.Add(standardVersion, lowerSupportImplementVersions);
+    i++;
+}
+
+Console.WriteLine("以下各种.NET的实现，支持了 .NET Standard 2.1的最低版本是：");
+Console.WriteLine("====");
+foreach(var lowlowerSupportImplementVersion in dotnetStandardQuery["2.1"]){
+    Console.WriteLine("* "+lowlowerSupportImplementVersion);
+}
+

data/1..NET初阶/1.入门/5..NET Standard概述/StandardQuery/StandardQuery.csproj

+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net6.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

data/1..NET初阶/1.入门/5..NET Standard概述/config.json

@@ -2,5 +2,7 @@
   "node_id": "csharp-65d2fd88ed1e44a6a646be4f3c302e50",
   "keywords": [],
   "children": [],
-  "export": []
+  "export": [
+      "StandardQuery.json"
+  ]
 }
\ No newline at end of file