添加项目文件。

LearnCsharp.sln

@@ -0,0 +1,25 @@
+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.3.32929.385
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "LearnCsharp", "LearnCsharp\LearnCsharp.csproj", "{95A3676E-9317-44A3-8D8A-0CC84A3A5275}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{95A3676E-9317-44A3-8D8A-0CC84A3A5275}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{95A3676E-9317-44A3-8D8A-0CC84A3A5275}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{95A3676E-9317-44A3-8D8A-0CC84A3A5275}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{95A3676E-9317-44A3-8D8A-0CC84A3A5275}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {89031123-55F4-40EB-B5AC-F6D142D6AB22}
+	EndGlobalSection
+EndGlobal

LearnCsharp/Decoder.cs

@@ -0,0 +1,33 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Base64Tools
+{
+    internal class Decoder
+    {
+        public static string Decode(string value)
+        {
+            if (value == null || value == "")
+            {
+                Console.WriteLine("请输入要解码的字符串：\a");
+                Console.WriteLine("---\n");
+                return "false";
+            }
+            else
+            {
+                try
+                {
+                    byte[] bytes = Convert.FromBase64String(value);
+                    return Encoding.UTF8.GetString(bytes);
+                }
+                catch (FormatException)
+                {
+                    return "false";
+                }
+            }
+        }
+    }
+}

LearnCsharp/LearnCsharp.csproj

@@ -0,0 +1,23 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net6.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <FileVersion></FileVersion>
+    <AssemblyVersion></AssemblyVersion>
+    <NeutralLanguage>zh-CN</NeutralLanguage>
+    <PackageIcon></PackageIcon>
+    <Copyright>2022©HRxiaohu</Copyright>
+    <Product></Product>
+    <AssemblyName>Base64Tools</AssemblyName>
+    <RootNamespace>Base64Tools</RootNamespace>
+    <ApplicationIcon>下载.ico</ApplicationIcon>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Content Include="下载.ico" />
+  </ItemGroup>
+
+</Project>

LearnCsharp/Main.cs

@@ -0,0 +1,62 @@
+using static Base64Tools.Uncoder;
+using static Base64Tools.Decoder;
+using System.Text;
+
+namespace Base64Tools
+{
+    class Tools
+    {
+        public static void Main(string[] args)
+        {
+            Console.WriteLine("----------------------------------------------------------------");
+            Console.WriteLine(" ____                  __   _  _   _____                     _\r\n| __ )  __ _ ___  ___ / /_ | || | | ____|_ __   ___ ___   __| | ___ _ __\r\n|  _ \\ / _` / __|/ _ | '_ \\| || |_|  _| | '_ \\ / __/ _ \\ / _` |/ _ | '__|\r\n| |_) | (_| \\__ |  __| (_) |__   _| |___| | | | (_| (_) | (_| |  __| |\r\n|____/ \\__,_|___/\\___|\\___/   |_| |_____|_| |_|\\___\\___/ \\__,_|\\___|_|\n");
+            Console.WriteLine("----------------------------------------------------------------");
+        start:
+            Console.WriteLine("您是想进行解码还是编码呢？请输入 解码/编码");
+            string answer = Console.ReadLine();
+            if (answer == "解码")
+            {
+            decoder:
+                Console.WriteLine("请输入要解码的Base64字符串");
+                string base64 = Console.ReadLine();
+                string base64Return = Decode(base64);
+                if (base64Return == "false")
+                {
+                    Console.WriteLine("请输入正确的Base64字符串\a");
+                    Console.WriteLine("---\a");
+                    goto decoder;
+                }
+                else
+                {
+                    Console.WriteLine("原文为:"+base64Return+"\n\a");
+                    Console.WriteLine("解码完毕");
+                    Console.WriteLine("---\n");
+                }
+            }
+            else if (answer == "编码")
+            {
+            uncoder:
+                Console.WriteLine("请输入要编码的Base64字符串:");
+                string base64 = Console.ReadLine();
+                string base64Return = Uncode(base64);
+                if (base64Return == "false")
+                {
+                    Console.WriteLine("请输入正确的Base64字符串\a");
+                    Console.WriteLine("---\n");
+                    goto uncoder;
+                }
+                else
+                {
+                    Console.WriteLine("原文为:"+base64Return +"\n\a");
+                    Console.WriteLine("编码完毕");
+                    Console.WriteLine("---\n");
+                }
+            }
+            else
+            {
+                Console.WriteLine("请输入正确的选项\n\a");
+                goto start;
+            }
+        }       
+    }
+}

LearnCsharp/Uncoder.cs

@@ -0,0 +1,32 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Base64Tools
+{
+    internal class Uncoder
+    {
+        public static string Uncode(string value)
+        {
+            if (value == null || value == "")
+            {
+                Console.WriteLine("请输入要解码的字符串\n\a");
+                return "false";
+            }
+            else
+            {
+                try
+                {
+                    byte[] bytes = Encoding.UTF8.GetBytes(value);
+                    return Convert.ToBase64String(bytes);
+                }
+                catch (FormatException)
+                {
+                    return "false";
+                }
+            }
+        }
+    }
+}