C++到C#核心语法对照指南

原文链接：https://www.progdomain.com/652/

C++到C#核心语法对照指南

一、基础语法对比

1. 程序入口点

C++:

int main(int argc, char* argv[]) {std::cout << "Hello World!" << std::endl;return 0;
}

C#:

// 传统方式
class Program 
{static void Main(string[] args){Console.WriteLine("Hello World!");}
}// C# 9.0+ 顶级语句
Console.WriteLine("Hello World!");

2. 变量声明与初始化

C++:

// 基本类型
int number = 42;
double pi = 3.14;
bool flag = true;// 指针
int* ptr = new int(42);
delete ptr;// 智能指针
std::unique_ptr<int> smartPtr(new int(42));
std::shared_ptr<int> sharedPtr = std::make_shared<int>(42);// 常量
const int MAX_VALUE = 100;
constexpr int COMPUTED = 10 * 10;

C#:

// 基本类型
int number = 42;
double pi = 3.14;
bool flag = true;// 引用类型
object obj = new();  // C# 9.0+简化语法
string str = "Hello";// 常量
const int MaxValue = 100;
readonly int computed = 10 * 10;// var关键字（类型推断）
var inferred = 42;    // 推断为int
var text = "Hello";   // 推断为string

3. 数组声明与使用

C++:

// 固定数组
int arr1[5] = {1, 2, 3, 4, 5};// 动态数组
int* arr2 = new int[5];
delete[] arr2;// vector（动态数组）
std::vector<int> vec = {1, 2, 3, 4, 5};
vec.push_back(6);// 多维数组
int matrix[3][3] = {{1,2,3}, {4,5,6}, {7,8,9}};

C#:

// 一维数组
int[] arr1 = { 1, 2, 3, 4, 5 };// 动态创建
int[] arr2 = new int[5];// List（动态列表）
List<int> list = new() { 1, 2, 3, 4, 5 };
list.Add(6);// 多维数组
int[,] matrix = { {1, 2, 3}, {4, 5, 6}, {7, 8, 9} 
};// 交错数组
int[][] jaggedArray = new int[3][];
jaggedArray[0] = new int[] { 1, 2, 3 };

4. 字符串处理

C++:

// 字符串声明
const char* str1 = "Hello";
std::string str2 = "World";// 字符串连接
std::string result = str2 + " " + str1;// 字符串格式化
char buffer[100];
sprintf(buffer, "Value: %d", 42);// 使用stringstream
std::stringstream ss;
ss << "Value: " << 42;
std::string formatted = ss.str();// 字符串分割
std::string input = "a,b,c";
std::stringstream ss(input);
std::string token;
std::vector<std::string> tokens;
while (std::getline(ss, token, ',')) {tokens.push_back(token);
}

C#:

// 字符串声明
string str1 = "Hello";
string str2 = "World";// 字符串连接
string result1 = str1 + " " + str2;
string result2 = string.Concat(str1, " ", str2);
string result3 = $"{str1} {str2}";  // 字符串插值// 字符串格式化
string formatted1 = string.Format("Value: {0}", 42);
string formatted2 = $"Value: {42}";// 字符串分割
string input = "a,b,c";
string[] tokens = input.Split(',');// 字符串构建器（高效字符串操作）
StringBuilder sb = new();
sb.Append("Hello");
sb.Append(" World");
string final = sb.ToString();

二、面向对象编程对比

1. 类的定义和继承

C++:

// Animal.h
class Animal {
protected:std::string name;public:Animal(const std::string& n) : name(n) {}virtual ~Animal() = default;virtual void MakeSound() = 0;virtual std::string GetName() const { return name; }
};// Dog.h
class Dog : public Animal {
private:int age;public:Dog(const std::string& n, int a) : Animal(n), age(a) {}void MakeSound() override {std::cout << "Woof!" << std::endl;}
};

C#:

public abstract class Animal
{protected string Name { get; set; }protected Animal(string name){Name = name;}public abstract void MakeSound();public virtual string GetName() => Name;
}public class Dog : Animal
{private int age;public Dog(string name, int age) : base(name){this.age = age;}public override void MakeSound(){Console.WriteLine("Woof!");}
}

2. 属性实现

C++:

class Person {
private:std::string name;int age;public:// Getter和Setter方法std::string GetName() const { return name; }void SetName(const std::string& value) { name = value; }int GetAge() const { return age; }void SetAge(int value) {if (value >= 0) age = value;}// 只读方法std::string GetFullInfo() const {return name + ", " + std::to_string(age) + " years old";}
};

C#:

public class Person
{// 自动属性public string Name { get; set; }// 带验证的完整属性private int age;public int Age{get => age;set => age = value >= 0 ? value : throw new ArgumentException("Age cannot be negative");}// 只读属性public string FullInfo => $"{Name}, {Age} years old";// 计算属性public bool IsAdult => Age >= 18;// 带后备字段的属性private string email;public string Email{get => email;set => email = value?.ToLower();}
}

3. 接口实现

C++:

// 使用抽象类模拟接口
class IMovable {
public:virtual ~IMovable() = default;virtual void Move() = 0;virtual double GetSpeed() = 0;virtual void SetSpeed(double speed) = 0;
};class IDrawable {
public:virtual ~IDrawable() = default;virtual void Draw() = 0;
};// 实现多个接口
class Car : public IMovable, public IDrawable {
private:double speed;public:void Move() override {std::cout << "Moving at " << speed << std::endl;}double GetSpeed() override { return speed; }void SetSpeed(double s) override { speed = s; }void Draw() override {std::cout << "Drawing car" << std::endl;}
};

C#:

public interface IMovable
{void Move();double Speed { get; set; }
}public interface IDrawable
{void Draw();
}// 实现多个接口
public class Car : IMovable, IDrawable
{public double Speed { get; set; }public void Move(){Console.WriteLine($"Moving at {Speed}");}public void Draw(){Console.WriteLine("Drawing car");}
}// C# 8.0+ 接口默认实现
public interface ILogger
{void Log(string message) => Console.WriteLine(message);void LogError(string message) => Console.WriteLine($"Error: {message}");
}

4. 泛型/模板对比

C++:

// 模板类
template<typename T>
class Container {
private:T data;public:void SetData(const T& value) { data = value; }T GetData() const { return data; }
};// 模板函数
template<typename T>
T Max(T a, T b) {return (a > b) ? a : b;
}// 模板特化
template<>
class Container<bool> {
private:bool data;
public:void SetData(bool value) { data = value; }bool GetData() const { return data; }
};// 模板约束（C++20 concepts）
template<typename T>
requires std::integral<T>
T Add(T a, T b) {return a + b;
}

C#:

// 泛型类
public class Container<T>
{private T data;public T Data{get => data;set => data = value;}
}// 泛型方法
public T Max<T>(T a, T b) where T : IComparable<T>
{return a.CompareTo(b) > 0 ? a : b;
}// 多重约束
public class Repository<T> where T : class, IEntity, new()
{public T CreateNew() => new T();
}// 泛型接口
public interface IRepository<T> where T : class
{T GetById(int id);void Save(T entity);
}// 协变和逆变
public interface IReader<out T>  // 协变
{T Read();
}public interface IWriter<in T>   // 逆变
{void Write(T value);
}

三、高级特性对比

1. 异常处理

C++:

class DatabaseException : public std::exception {
public:const char* what() const noexcept override {return "Database error occurred";}
};void ProcessData() {try {// 可能抛出异常的代码throw DatabaseException();// 多个异常throw std::runtime_error("Other error");}catch (const DatabaseException& e) {std::cerr << "Database error: " << e.what() << std::endl;throw; // 重新抛出}catch (const std::exception& e) {std::cerr << "Standard exception: " << e.what() << std::endl;}catch (...) {std::cerr << "Unknown exception" << std::endl;}
}

C#:

public class DatabaseException : Exception
{public DatabaseException(string message) : base(message) { }public DatabaseException(string message, Exception inner) : base(message, inner) { }
}public void ProcessData()
{try{// 可能抛出异常的代码throw new DatabaseException("Connection failed");}catch (DatabaseException ex) when (ex.Message.Contains("Connection")){// 条件捕获（C# 6.0+）Logger.LogError(ex);throw; // 保留堆栈跟踪重新抛出}catch (Exception ex){Logger.LogError(ex);// 包装异常throw new ApplicationException("Processing failed", ex);}finally{// 清理代码，总是执行CleanupResources();}
}

2. 委托和事件

C++:

// 使用函数指针
typedef void (*CallbackFunc)(const std::string&);class EventEmitter {
private:CallbackFunc callback;public:void SetCallback(CallbackFunc cb) {callback = cb;}void Emit(const std::string& message) {if (callback) callback(message);}
};// 使用std::function
class ModernEmitter {
private:std::function<void(const std::string&)> callback;public:void SetCallback(const std::function<void(const std::string&)>& cb) {callback = cb;}void Emit(const std::string& message) {if (callback) callback(message);}
};

C#:

// 委托定义
public delegate void MessageHandler(string message);public class EventEmitter
{// 事件声明public event MessageHandler MessageReceived;// 事件触发protected virtual void OnMessageReceived(string message){MessageReceived?.Invoke(message);}// 内置委托类型public Action<string> Logger { get; set; }public Func<int, int, int> Calculator { get; set; }public void ProcessMessage(string msg){// 触发事件OnMessageReceived(msg);// 使用委托Logger?.Invoke(msg);int result = Calculator?.Invoke(5, 3) ?? 0;}
}// 使用示例
public void SetupEvents()
{var emitter = new EventEmitter();// 订阅事件emitter.MessageReceived += HandleMessage;// Lambda表达式emitter.MessageReceived += (msg) => Console.WriteLine(msg);// 委托赋值emitter.Logger = Console.WriteLine;emitter.Calculator = (x, y) => x + y;
}

3. 异步编程

C++:

// 使用std::future和std::async
#include <future>std::future<int> AsyncOperation() {return std::async(std::launch::async, []() {std::this_thread::sleep_for(std::chrono::seconds(1));return 42;});
}void ProcessAsync() {auto future = AsyncOperation();// ... 做其他工作 ...int result = future.get(); // 等待结果
}// 使用Promise
void ComplexAsyncOperation() {std::promise<int> promise;std::future<int> future = promise.get_future();std::thread([&promise]() {try {int result = PerformWork();promise.set_value(result);}catch (...) {promise.set_exception(std::current_exception());}}).detach();// ... 等待结果 ...try {int value = future.get();}catch (const std::exception& e) {// 处理错误}
}

C#:

public class AsyncExample
{// 异步方法public async Task<int> GetDataAsync(){await Task.Delay(1000); // 模拟异步操作return 42;}// 异步流public async IAsyncEnumerable<int> GenerateNumbersAsync(){for (int i = 0; i < 10; i++){await Task.Delay(100);yield return i;}}// 并行处理public async Task ProcessItemsAsync(IEnumerable<string> items){// 并行异步操作var tasks = items.Select(async item =>{await Task.Delay(100);return await ProcessItemAsync(item);});// 等待所有任务完成var results = await Task.WhenAll(tasks);}// 异步异常处理public async Task SafeOperationAsync(){try{await Task.Delay(100);throw new Exception("Async error");}catch (Exception ex){await LogErrorAsync(ex);throw;}}// 取消操作public async Task CancellableOperationAsync(CancellationToken cancellationToken){while (!cancellationToken.IsCancellationRequested){await Task.Delay(100, cancellationToken);// 执行工作}}
}// 使用示例
public async Task Example()
{var asyncExample = new AsyncExample();// 等待单个任务int result = await asyncExample.GetDataAsync();// 处理异步流await foreach (var number in asyncExample.GenerateNumbersAsync()){Console.WriteLine(number);}// 使用取消令牌using var cts = new CancellationTokenSource();cts.CancelAfter(TimeSpan.FromSeconds(5)); // 5秒后取消try{await asyncExample.CancellableOperationAsync(cts.Token);}catch (OperationCanceledException){Console.WriteLine("Operation was cancelled");}
}

四、集合操作和LINQ对比

C++:

// STL容器操作
vector<int> numbers = {1, 2, 3, 4, 5};// 过滤
vector<int> filtered;
copy_if(numbers.begin(), numbers.end(), back_inserter(filtered),[](int n) { return n % 2 == 0; });// 转换
vector<string> strings;
transform(numbers.begin(), numbers.end(),back_inserter(strings),[](int n) { return std::to_string(n); });// 排序
sort(numbers.begin(), numbers.end());
sort(numbers.begin(), numbers.end(), [](int a, int b) { return a > b; });// 聚合
int sum = accumulate(numbers.begin(), numbers.end(), 0);
auto maxElement = max_element(numbers.begin(), numbers.end());// 查找
auto it = find(numbers.begin(), numbers.end(), 3);
bool exists = it != numbers.end();

C#:

// LINQ操作
var numbers = new List<int> { 1, 2, 3, 4, 5 };// 过滤
var filtered = numbers.Where(n => n % 2 == 0);// 转换
var strings = numbers.Select(n => n.ToString());// 排序
var ordered = numbers.OrderBy(n => n);
var descending = numbers.OrderByDescending(n => n);// 聚合
var sum = numbers.Sum();
var max = numbers.Max();
var avg = numbers.Average();// 复杂查询
var result = numbers.Where(n => n > 2).OrderBy(n => n).Select(n => new { Number = n, Square = n * n }).ToList();// 分组
var groups = numbers.GroupBy(n => n % 2).Select(g => new { Key = g.Key, Items = g.ToList() });// 连接
var list1 = new List<(int Id, string Name)> { (1, "John"), (2, "Jane") };
var list2 = new List<(int Id, int Score)> { (1, 100), (2, 95) };var joined = list1.Join(list2,l1 => l1.Id,l2 => l2.Id,(l1, l2) => new { l1.Name, l2.Score });

2. 文件操作

C++:

// 文件写入
void WriteFile() {ofstream file("data.txt");if (file.is_open()) {file << "Hello World" << endl;file.close();}
}// 文件读取
void ReadFile() {ifstream file("data.txt");string line;if (file.is_open()) {while (getline(file, line)) {cout << line << endl;}file.close();}
}// 二进制文件操作
void BinaryFileOps() {// 写入ofstream file("data.bin", ios::binary);int data = 42;file.write(reinterpret_cast<char*>(&data), sizeof(data));file.close();// 读取ifstream inFile("data.bin", ios::binary);inFile.read(reinterpret_cast<char*>(&data), sizeof(data));inFile.close();
}

C#:

public class FileOperations
{// 同步文件操作public void WriteFile(){File.WriteAllText("data.txt", "Hello World");// 使用StreamWriterusing var writer = new StreamWriter("data.txt");writer.WriteLine("Hello World");}// 异步文件操作public async Task WriteFileAsync(){await File.WriteAllTextAsync("data.txt", "Hello World");// 使用StreamWriterawait using var writer = new StreamWriter("data.txt");await writer.WriteLineAsync("Hello World");}// 文件读取public async Task<string> ReadFileAsync(){// 简单读取string content = await File.ReadAllTextAsync("data.txt");// 流式读取await using var stream = File.OpenRead("data.txt");using var reader = new StreamReader(stream);string? line;while ((line = await reader.ReadLineAsync()) != null){Console.WriteLine(line);}return content;}// 文件监控public void WatchFile(){var watcher = new FileSystemWatcher(".");watcher.Changed += (s, e) => Console.WriteLine($"File {e.Name} changed");watcher.EnableRaisingEvents = true;}// 文件操作异常处理public async Task SafeFileOperationAsync(){try{await File.WriteAllTextAsync("data.txt", "Hello World");}catch (IOException ex){Console.WriteLine($"IO Error: {ex.Message}");}catch (UnauthorizedAccessException ex){Console.WriteLine($"Access Error: {ex.Message}");}}
}

3. 网络操作

C++:

// 使用Boost.Asio或原生Socket
#include <boost/asio.hpp>using boost::asio::ip::tcp;void NetworkOperation() {try {boost::asio::io_context io_context;tcp::socket socket(io_context);tcp::resolver resolver(io_context);auto endpoints = resolver.resolve("example.com", "80");boost::asio::connect(socket, endpoints);boost::asio::write(socket, boost::asio::buffer("GET / HTTP/1.1\r\n\r\n"));char data[1024];size_t length = socket.read_some(boost::asio::buffer(data, 1024));}catch (std::exception& e) {std::cerr << e.what() << std::endl;}
}

C#:

public class NetworkOperations
{private readonly HttpClient _client = new();// HTTP GET请求public async Task<string> GetDataAsync(string url){try{var response = await _client.GetAsync(url);response.EnsureSuccessStatusCode();return await response.Content.ReadAsStringAsync();}catch (HttpRequestException ex){Console.WriteLine($"HTTP Error: {ex.Message}");throw;}}// HTTP POST请求public async Task<string> PostDataAsync(string url, object data){var content = new StringContent(JsonSerializer.Serialize(data),Encoding.UTF8,"application/json");var response = await _client.PostAsync(url, content);return await response.Content.ReadAsStringAsync();}// WebSocket操作public async Task WebSocketOperationAsync(){using var ws = new ClientWebSocket();await ws.ConnectAsync(new Uri("ws://example.com"), CancellationToken.None);var buffer = new byte[1024];while (ws.State == WebSocketState.Open){var result = await ws.ReceiveAsync(new ArraySegment<byte>(buffer), CancellationToken.None);if (result.MessageType == WebSocketMessageType.Close){await ws.CloseAsync(WebSocketCloseStatus.NormalClosure,string.Empty,CancellationToken.None);}else{// 处理接收到的数据}}}
}

五、并发编程对比

1. 线程操作

C++:

#include <thread>
#include <mutex>class ThreadExample {
private:std::mutex mtx;public:// 基本线程创建void BasicThread() {std::thread t([]() {std::cout << "Thread running" << std::endl;});t.join(); // 等待线程完成}// 互斥锁void MutexExample() {std::lock_guard<std::mutex> lock(mtx);// 临界区代码}// 条件变量void ConditionVariableExample() {std::condition_variable cv;std::mutex mutex;bool ready = false;std::thread worker([&]() {std::unique_lock<std::mutex> lock(mutex);cv.wait(lock, [&]() { return ready; });// 执行工作});{std::lock_guard<std::mutex> lock(mutex);ready = true;}cv.notify_one();worker.join();}
};

C#:

public class ThreadExample
{private readonly object _lock = new();// 基本线程创建public void BasicThread(){var thread = new Thread(() =>{Console.WriteLine("Thread running");});thread.Start();thread.Join(); // 等待线程完成}// 线程池使用public void ThreadPoolExample(){ThreadPool.QueueUserWorkItem(state =>{Console.WriteLine("Work item running");});}// 锁定示例public void LockExample(){lock (_lock){// 临界区代码}}// Monitor使用public void MonitorExample(){Monitor.Enter(_lock);try{// 临界区代码}finally{Monitor.Exit(_lock);}}// 异步等待public async Task WaitExample(){using var semaphore = new SemaphoreSlim(1);await semaphore.WaitAsync();try{// 临界区代码}finally{semaphore.Release();}}
}

2. 并发集合

C++:

#include <concurrent_queue>
#include <concurrent_vector>class ConcurrentCollections {
public:void QueueExample() {concurrency::concurrent_queue<int> queue;// 添加元素queue.push(42);// 尝试获取元素int value;if (queue.try_pop(value)) {// 处理值}}void VectorExample() {concurrency::concurrent_vector<int> vec;// 并发添加元素vec.push_back(1);// 并发访问for (const auto& item : vec) {// 处理元素}}
};

C#:

public class ConcurrentCollections
{// 并发队列public async Task ConcurrentQueueExample(){var queue = new ConcurrentQueue<int>();// 添加元素queue.Enqueue(42);// 尝试获取元素if (queue.TryDequeue(out int result)){Console.WriteLine(result);}// 并行操作await Parallel.ForEachAsync(Enumerable.Range(0, 100),async (i, token) =>{queue.Enqueue(i);await Task.Delay(10, token);});}// 并发字典public void ConcurrentDictionaryExample(){var dict = new ConcurrentDictionary<string, int>();// 添加或更新dict.AddOrUpdate("key",1,                              // 添加的值(key, oldValue) => oldValue + 1 // 更新的值);// 获取或添加var value = dict.GetOrAdd("key", 0);// 线程安全的更新dict.AddOrUpdate("counter",1,(key, old) => old + 1);}// 并发包public void ConcurrentBagExample(){var bag = new ConcurrentBag<int>();// 添加元素bag.Add(42);// 尝试获取元素if (bag.TryTake(out int item)){Console.WriteLine(item);}}
}

3. 任务并行库（TPL）

C++:

#include <execution>
#include <algorithm>class ParallelProcessing {
public:void ParallelAlgorithms() {std::vector<int> vec(1000);// 并行填充std::fill(std::execution::par,vec.begin(), vec.end(), 42);// 并行排序std::sort(std::execution::par,vec.begin(), vec.end());// 并行转换std::transform(std::execution::par,vec.begin(), vec.end(),vec.begin(),[](int x) { return x * 2; });}
};

C#:

public class ParallelProcessing
{// 并行For循环public void ParallelForExample(){Parallel.For(0, 1000, i =>{// 并行处理每个索引ProcessItem(i);});}// 并行ForEachpublic void ParallelForEachExample(){var items = Enumerable.Range(0, 1000);Parallel.ForEach(items,new ParallelOptions { MaxDegreeOfParallelism = 4 },item =>{// 并行处理每个项ProcessItem(item);});}// 并行LINQpublic void ParallelLinqExample(){var numbers = Enumerable.Range(0, 1000);var result = numbers.AsParallel().Where(n => n % 2 == 0).Select(n => n * 2).OrderBy(n => n).ToList();}// 任务并行public async Task ParallelTasksExample(){var tasks = new List<Task<int>>();// 创建多个任务for (int i = 0; i < 10; i++){tasks.Add(Task.Run(async () =>{await Task.Delay(100);return await ProcessItemAsync(i);}));}// 等待所有任务完成var results = await Task.WhenAll(tasks);// 获取第一个完成的任务var firstResult = await Task.WhenAny(tasks);}
}

六、反射和元数据编程

1. 反射基础

C++:

// C++没有内置的反射机制，通常使用自定义宏或第三方库
#include <typeinfo>class ReflectionExample {
public:// 使用RTTI (Run-Time Type Information)void TypeInfo() {int x = 42;const std::type_info& typeInfo = typeid(x);std::cout << typeInfo.name() << std::endl;}
};// 模拟反射的一种方式
#define REGISTER_PROPERTY(Type, Name) \Type Name; \const char* Get##Name() { return #Name; }class Person {REGISTER_PROPERTY(std::string, name)REGISTER_PROPERTY(int, age)
};

C#:

public class ReflectionExample
{public void TypeInformation(){// 获取类型信息Type type = typeof(string);Type type2 = "Hello".GetType();// 检查类型信息Console.WriteLine($"Type: {type.Name}");Console.WriteLine($"Is class: {type.IsClass}");Console.WriteLine($"Base type: {type.BaseType?.Name}");}public void MemberInformation(){Type type = typeof(Person);// 获取所有公共属性var properties = type.GetProperties();// 获取所有公共方法var methods = type.GetMethods();// 获取特定成员var property = type.GetProperty("Name");var method = type.GetMethod("ToString");// 获取特性var attributes = type.GetCustomAttributes();}public void DynamicInstantiation(){// 动态创建实例Type type = typeof(Person);object instance = Activator.CreateInstance(type);// 动态调用方法var method = type.GetMethod("SayHello");method?.Invoke(instance, null);// 动态设置属性var property = type.GetProperty("Name");property?.SetValue(instance, "John");}
}// 使用特性的示例
[Serializable]
public class Person
{[Required]public string Name { get; set; }[Range(0, 150)]public int Age { get; set; }public void SayHello(){Console.WriteLine($"Hello, I'm {Name}");}
}

2. 序列化

C++:

// 使用Boost.Serialization或自定义序列化
#include <boost/archive/text_oarchive.hpp>
#include <boost/archive/text_iarchive.hpp>class SerializableClass {
private:std::string name;int age;friend class boost::serialization::access;template<class Archive>void serialize(Archive & ar, const unsigned int version){ar & name;ar & age;}public:void Save() {std::ofstream file("data.txt");boost::archive::text_oarchive oa(file);oa << *this;}void Load() {std::ifstream file("data.txt");boost::archive::text_iarchive ia(file);ia >> *this;}
};

C#:

public class SerializationExample
{// JSON序列化public string JsonSerialize<T>(T obj){return JsonSerializer.Serialize(obj, new JsonSerializerOptions{WriteIndented = true,PropertyNamingPolicy = JsonNamingPolicy.CamelCase});}public T JsonDeserialize<T>(string json){return JsonSerializer.Deserialize<T>(json);}// XML序列化public string XmlSerialize<T>(T obj){var serializer = new XmlSerializer(typeof(T));using var writer = new StringWriter();serializer.Serialize(writer, obj);return writer.ToString();}public T XmlDeserialize<T>(string xml){var serializer = new XmlSerializer(typeof(T));using var reader = new StringReader(xml);return (T)serializer.Deserialize(reader);}// 二进制序列化public byte[] BinarySerialize<T>(T obj){using var stream = new MemoryStream();var formatter = new BinaryFormatter();formatter.Serialize(stream, obj);return stream.ToArray();}public T BinaryDeserialize<T>(byte[] data){using var stream = new MemoryStream(data);var formatter = new BinaryFormatter();return (T)formatter.Deserialize(stream);}
}// 序列化示例类
[Serializable]
public class Person
{[JsonPropertyName("fullName")]public string Name { get; set; }[JsonIgnore]public int InternalId { get; set; }[XmlElement("DateOfBirth")]public DateTime BirthDate { get; set; }
}

3. 依赖注入

C++:

// C++通常使用工厂模式或依赖注入容器
class ILogger {
public:virtual ~ILogger() = default;virtual void Log(const std::string& message) = 0;
};class ConsoleLogger : public ILogger {
public:void Log(const std::string& message) override {std::cout << message << std::endl;}
};class Service {
private:std::shared_ptr<ILogger> logger;public:Service(std::shared_ptr<ILogger> logger) : logger(logger) {}void DoWork() {logger->Log("Working...");}
};// 使用示例
auto logger = std::make_shared<ConsoleLogger>();
Service service(logger);

C#:

// 使用内置依赖注入
public class Startup
{public void ConfigureServices(IServiceCollection services){// 注册服务services.AddSingleton<ILogger, ConsoleLogger>();services.AddScoped<IUserService, UserService>();services.AddTransient<IEmailSender, SmtpEmailSender>();// 注册带配置的服务services.Configure<EmailSettings>(configuration.GetSection("Email"));// 注册工厂services.AddSingleton<IDatabase>(sp =>{var config = sp.GetRequiredService<IConfiguration>();return new Database(config.GetConnectionString("Default"));});}
}// 服务类
public interface IUserService
{Task<User> GetUserAsync(int id);
}public class UserService : IUserService
{private readonly ILogger<UserService> _logger;private readonly IEmailSender _emailSender;// 构造函数注入public UserService(ILogger<UserService> logger,IEmailSender emailSender){_logger = logger;_emailSender = emailSender;}public async Task<User> GetUserAsync(int id){_logger.LogInformation($"Getting user {id}");// 实现逻辑return await Task.FromResult(new User());}
}// 控制器示例
public class UserController : ControllerBase
{private readonly IUserService _userService;public UserController(IUserService userService){_userService = userService;}[HttpGet("{id}")]public async Task<ActionResult<User>> GetUser(int id){return await _userService.GetUserAsync(id);}
}

七、性能优化和内存管理

1. 内存管理

C++:

class MemoryManagement {
public:// 手动内存管理void RawPointers() {// 堆分配int* ptr = new int(42);delete ptr;  // 必须手动释放// 数组int* arr = new int[100];delete[] arr;}// 智能指针void SmartPointers() {// 独占所有权std::unique_ptr<int> unique(new int(42));// 共享所有权std::shared_ptr<int> shared = std::make_shared<int>(42);// 弱引用std::weak_ptr<int> weak = shared;}// RAII模式class ResourceHandler {FILE* file;public:ResourceHandler(const char* filename) {file = fopen(filename, "r");}~ResourceHandler() {if (file) fclose(file);}};
};

C#:

public class MemoryManagement
{// 托管资源public class ManagedResources{private readonly List<byte[]> _cache = new();public void AllocateMemory(){// GC会自动管理这些对象var data = new byte[1024];_cache.Add(data);}}// 非托管资源管理public class UnmanagedResources : IDisposable{private bool _disposed;private IntPtr _nativeResource;private readonly SafeHandle _managedResource;public UnmanagedResources(){_nativeResource = Marshal.AllocHGlobal(100);_managedResource = new SafeFileHandle(IntPtr.Zero, true);}public void Dispose(){Dispose(true);GC.SuppressFinalize(this);}protected virtual void Dispose(bool disposing){if (!_disposed){if (disposing){// 释放托管资源_managedResource?.Dispose();}// 释放非托管资源if (_nativeResource != IntPtr.Zero){Marshal.FreeHGlobal(_nativeResource);_nativeResource = IntPtr.Zero;}_disposed = true;}}~UnmanagedResources(){Dispose(false);}}// 内存优化技巧public class MemoryOptimization{// 使用对象池private readonly ObjectPool<StringBuilder> _stringBuilderPool =new DefaultObjectPool<StringBuilder>(new StringBuilderPooledObjectPolicy());public string BuildString(){var sb = _stringBuilderPool.Get();try{sb.Append("Hello").Append(" World");return sb.ToString();}finally{_stringBuilderPool.Return(sb);}}// 使用Span<T>public void SpanExample(){Span<byte> buffer = stackalloc byte[100];// 直接在栈上操作，避免堆分配ReadOnlySpan<char> text = "Hello World".AsSpan();// 无需创建新的字符串实例}}
}

2. 性能优化技巧

C++:

class PerformanceOptimization {
public:// 内联函数inline int FastOperation(int x) {return x * 2;}// 常量表达式constexpr int ConstantCalculation(int x) {return x * x;}// 移动语义std::vector<int> CreateVector() {std::vector<int> vec(1000);return std::move(vec);  // 避免复制}// 视图和引用void ProcessLargeData(const std::vector<int>& data) {// 通过引用避免复制for (const auto& item : data) {// 处理数据}}
};

C#:

public class PerformanceOptimization
{// 值类型优化public struct Point{public int X { get; set; }public int Y { get; set; }}// 内存池化private readonly ArrayPool<byte> _arrayPool = ArrayPool<byte>.Shared;public async Task ProcessDataAsync(){byte[] buffer = _arrayPool.Rent(1024);try{await ProcessBufferAsync(buffer);}finally{_arrayPool.Return(buffer);}}// 避免装箱public struct GenericValue<T> where T : struct{private readonly T _value;public GenericValue(T value){_value = value;}public override string ToString() => _value.ToString();}// 高效字符串处理public string BuildLargeString(){var sb = new StringBuilder();for (int i = 0; i < 1000; i++){sb.Append($"Item {i},");}return sb.ToString();}// 异步优化public async Task<IEnumerable<T>> ProcessItemsAsync<T>(IEnumerable<T> items,Func<T, Task> processor){// 批量处理var batches = items.Chunk(100);foreach (var batch in batches){var tasks = batch.Select(processor);await Task.WhenAll(tasks);}return items;}// SIMD操作public void SimdOperation(){if (Vector.IsHardwareAccelerated){var vector1 = new Vector<float>(new float[] { 1, 2, 3, 4 });var vector2 = new Vector<float>(new float[] { 5, 6, 7, 8 });var result = vector1 + vector2;}}
}

3. 调试和性能分析

C++:

class Debugging {
public:void DebugExample() {#ifdef _DEBUGstd::cout << "Debug mode" << std::endl;#endif// 断言assert(CheckCondition());// 性能计时auto start = std::chrono::high_resolution_clock::now();// 执行代码auto end = std::chrono::high_resolution_clock::now();auto duration = std::chrono::duration_cast<std::chrono::milliseconds>(end - start);}private:bool CheckCondition() {return true;}
};

C#:

public class Debugging
{private readonly ILogger<Debugging> _logger;// 调试辅助方法[Conditional("DEBUG")]public void DebugMethod(){Debug.WriteLine("Debug information");Trace.WriteLine("Trace information");Debug.Assert(CheckCondition(), "Condition failed");}// 性能计数器public async Task MeasurePerformance(){using var activity = Activity.StartNew("OperationName");var sw = Stopwatch.StartNew();try{await PerformOperation();}finally{sw.Stop();_logger.LogInformation("Operation completed in {Milliseconds}ms", sw.ElapsedMilliseconds);}}// 诊断工具public void DiagnosticsExample(){// 内存使用var process = Process.GetCurrentProcess();var memoryUsed = process.WorkingSet64;// GC信息var gcInfo = GC.GetGCMemoryInfo();var heapSize = gcInfo.HeapSizeBytes;// 线程信息var threadCount = Process.GetCurrentProcess().Threads.Count;}// 性能计数器public class PerformanceMonitoring{private readonly Metrics _metrics = new();public async Task MonitorOperation(){using (_metrics.MeasureHistogram("operation_duration","Operation duration in seconds")){await PerformOperation();}}}
}

这些示例展示了C++和C#在性能优化和内存管理方面的不同方法。C++提供了更直接的内存控制，而C#提供了更多的内置工具和自动化机制。

关键区别：

1. C++需要手动管理内存，C#有GC
2. C++可以直接操作内存，C#主要通过安全的抽象
3. C++性能优化更依赖于底层控制，C#提供了更多高级工具
4. C#有更完善的性能分析和诊断工具支持

建议C++开发者在转向C#时：

1. 了解GC的工作原理
2. 熟悉C#的性能优化工具
3. 使用适当的内存管理模式
4. 利用C#提供的诊断和分析工具