cpp

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Original

English

🇨🇳

Translation

Chinese

C++ Development

现代C++开发

Write safe, performant modern C++ code.

编写安全、高性能的现代C++代码。

When to Use

适用场景

Writing C++ code
Memory management issues
Template metaprogramming
Performance optimization
Legacy C++ modernization

编写C++代码
内存管理问题
模板元编程
性能优化
遗留C++代码现代化

Modern C++ Patterns

现代C++设计模式

Smart Pointers

智能指针

cpp

// Unique ownership
auto ptr = std::make_unique<Resource>();
process(std::move(ptr));

// Shared ownership
auto shared = std::make_shared<Resource>();
auto copy = shared;  // Reference count: 2

// Weak reference (no ownership)
std::weak_ptr<Resource> weak = shared;
if (auto locked = weak.lock()) {
    // Use locked
}

cpp

// Unique ownership
auto ptr = std::make_unique<Resource>();
process(std::move(ptr));

// Shared ownership
auto shared = std::make_shared<Resource>();
auto copy = shared;  // Reference count: 2

// Weak reference (no ownership)
std::weak_ptr<Resource> weak = shared;
if (auto locked = weak.lock()) {
    // Use locked
}

RAII

cpp

class FileHandle {
    FILE* handle_;
public:
    explicit FileHandle(const char* path)
        : handle_(fopen(path, "r")) {
        if (!handle_) throw std::runtime_error("Failed to open");
    }
    ~FileHandle() { if (handle_) fclose(handle_); }

    // Rule of 5
    FileHandle(const FileHandle&) = delete;
    FileHandle& operator=(const FileHandle&) = delete;
    FileHandle(FileHandle&& other) noexcept
        : handle_(std::exchange(other.handle_, nullptr)) {}
    FileHandle& operator=(FileHandle&& other) noexcept {
        std::swap(handle_, other.handle_);
        return *this;
    }
};

cpp

class FileHandle {
    FILE* handle_;
public:
    explicit FileHandle(const char* path)
        : handle_(fopen(path, "r")) {
        if (!handle_) throw std::runtime_error("Failed to open");
    }
    ~FileHandle() { if (handle_) fclose(handle_); }

    // Rule of 5
    FileHandle(const FileHandle&) = delete;
    FileHandle& operator=(const FileHandle&) = delete;
    FileHandle(FileHandle&& other) noexcept
        : handle_(std::exchange(other.handle_, nullptr)) {}
    FileHandle& operator=(FileHandle&& other) noexcept {
        std::swap(handle_, other.handle_);
        return *this;
    }
};

Containers and Algorithms

容器与算法

cpp

std::vector<int> nums = {3, 1, 4, 1, 5};

// Prefer algorithms over raw loops
std::sort(nums.begin(), nums.end());

auto it = std::find_if(nums.begin(), nums.end(),
    [](int n) { return n > 3; });

// Range-based for
for (const auto& num : nums) {
    std::cout << num << '\n';
}

// Structured bindings (C++17)
std::map<std::string, int> scores;
for (const auto& [name, score] : scores) {
    std::cout << name << ": " << score << '\n';
}

cpp

std::vector<int> nums = {3, 1, 4, 1, 5};

// Prefer algorithms over raw loops
std::sort(nums.begin(), nums.end());

auto it = std::find_if(nums.begin(), nums.end(),
    [](int n) { return n > 3; });

// Range-based for
for (const auto& num : nums) {
    std::cout << num << '\n';
}

// Structured bindings (C++17)
std::map<std::string, int> scores;
for (const auto& [name, score] : scores) {
    std::cout << name << ": " << score << '\n';
}

Templates

模板

cpp

// Concepts (C++20)
template<typename T>
concept Numeric = std::integral<T> || std::floating_point<T>;

template<Numeric T>
T sum(const std::vector<T>& values) {
    return std::accumulate(values.begin(), values.end(), T{});
}

// SFINAE (pre-C++20)
template<typename T,
    typename = std::enable_if_t<std::is_arithmetic_v<T>>>
T multiply(T a, T b) { return a * b; }

cpp

// Concepts (C++20)
template<typename T>
concept Numeric = std::integral<T> || std::floating_point<T>;

template<Numeric T>
T sum(const std::vector<T>& values) {
    return std::accumulate(values.begin(), values.end(), T{});
}

// SFINAE (pre-C++20)
template<typename T,
    typename = std::enable_if_t<std::is_arithmetic_v<T>>>
T multiply(T a, T b) { return a * b; }

Best Practices

最佳实践

Prefer
```
const
```
and
```
constexpr
```
Use smart pointers over raw pointers
Follow Rule of 0/5
Prefer STL algorithms
Use
```
std::string_view
```
for read-only strings
Enable warnings:
```
-Wall -Wextra -Wpedantic
```

优先使用
```
const
```
和
```
constexpr
```
用智能指针替代裸指针
遵循Rule of 0/5规则
优先使用STL算法
对只读字符串使用
```
std::string_view
```
启用警告：
```
-Wall -Wextra -Wpedantic
```

Common Issues

常见问题

Issue	Symptom	Fix
Memory leak	Growing memory	Use smart pointers
Dangling ptr	Crash/UB	Check lifetime
Buffer overflow	Crash/security	Use std::vector/span
Data race	Inconsistent state	mutex/atomic

问题	症状	修复方案
内存泄漏	内存持续增长	使用智能指针
悬垂指针	崩溃/未定义行为	检查对象生命周期
缓冲区溢出	崩溃/安全风险	使用std::vector/span
数据竞争	状态不一致	使用mutex/atomic

Examples

示例

Input: "Fix memory leak" Action: Replace raw pointers with smart pointers, ensure RAII

Input: "Modernize this C++ code" Action: Apply C++17/20 features, use STL, improve safety

输入： "修复内存泄漏" 操作： 用智能指针替换裸指针，确保遵循RAII原则

输入： "现代化这段C++代码" 操作： 应用C++17/20特性，使用STL，提升代码安全性