cpp

name	cpp
description	C++ modern C++17/20/23 with STL, smart pointers, and performance optimization. Use for .cpp files.

C++

Modern C++ development with smart pointers, RAII, and performance optimization.

When to Use

• Working with .cpp or .hpp files
• Systems programming and embedded
• Game development with Unreal Engine
• Performance-critical applications

Quick Start

#include <memory>
#include <string>
#include <vector>

class User {
public:
    User(std::string name, std::string email)
        : name_(std::move(name)), email_(std::move(email)) {}

    const std::string& name() const { return name_; }
    const std::string& email() const { return email_; }

private:
    std::string name_;
    std::string email_;
};

auto user = std::make_unique<User>("John", "[e-mail]");

Core Concepts

Smart Pointers

// unique_ptr - exclusive ownership
auto user = std::make_unique<User>("John");

// shared_ptr - shared ownership
auto shared = std::make_shared<Resource>();
auto copy = shared;  // ref count increases

// weak_ptr - non-owning observer
std::weak_ptr<Resource> observer = shared;
if (auto locked = observer.lock()) {
    // safe to use
}

// Never use raw new/delete for ownership

Move Semantics

class Buffer {
public:
    Buffer(size_t size) : data_(new char[size]), size_(size) {}

    // Move constructor
    Buffer(Buffer&& other) noexcept
        : data_(other.data_), size_(other.size_) {
        other.data_ = nullptr;
        other.size_ = 0;
    }

    // Move assignment
    Buffer& operator=(Buffer&& other) noexcept {
        if (this != &other) {
            delete[] data_;
            data_ = other.data_;
            size_ = other.size_;
            other.data_ = nullptr;
            other.size_ = 0;
        }
        return *this;
    }

    ~Buffer() { delete[] data_; }

private:
    char* data_;
    size_t size_;
};

Common Patterns

Modern C++ Features

// Structured bindings (C++17)
auto [name, age] = std::make_pair("John", 25);
for (const auto& [key, value] : map) { /* ... */ }

// std::optional (C++17)
std::optional<User> findUser(int id) {
    if (exists) return User{...};
    return std::nullopt;
}

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

template<Numeric T>
T add(T a, T b) { return a + b; }

// Ranges (C++20)
auto result = numbers
    | std::views::filter([](int n) { return n % 2 == 0; })
    | std::views::transform([](int n) { return n * 2; });

RAII Pattern

class FileHandle {
public:
    explicit FileHandle(const char* path)
        : file_(std::fopen(path, "r")) {
        if (!file_) throw std::runtime_error("Cannot open file");
    }

    ~FileHandle() { if (file_) std::fclose(file_); }

    // Delete copy
    FileHandle(const FileHandle&) = delete;
    FileHandle& operator=(const FileHandle&) = delete;

    // Allow move
    FileHandle(FileHandle&& other) noexcept : file_(other.file_) {
        other.file_ = nullptr;
    }

private:
    FILE* file_;
};

Best Practices

Do:

• Use smart pointers for ownership
• Apply RAII for resource management
• Use const and constexpr liberally
• Prefer std::string_view for read-only strings

Don't:

• Use raw new/delete for ownership
• Return raw pointers from functions
• Use C-style casts (use static_cast)
• Ignore compiler warnings

Troubleshooting

Error	Cause	Solution
Segmentation fault	Null pointer or buffer overflow	Use sanitizers, smart pointers
Memory leak	Missing delete	Use RAII, smart pointers
Undefined behavior	Dangling reference	Ensure lifetime validity

References

• C++ Reference
• ISO C++ Guidelines