What is the Rule of Five in C++?

Question

Accepted Answer

**Rule of Five** — extends Rule of Three with move semantics (C++11).

```cpp
class MyClass {
private:
    int* data;

public:
    // 1. Destructor
    ~MyClass() { delete data; }

// 2. Copy constructor
    MyClass(const MyClass& other) {
        data = new int(*other.data);
    }

// 3. Copy assignment
    MyClass& operator=(const MyClass& other) {
        if (this != &other) {
            *data = *other.data;
        }
        return *this;
    }

// 4. Move constructor
    MyClass(MyClass&& other) noexcept {
        data = other.data;
        other.data = nullptr;
    }

// 5. Move assignment
    MyClass& operator=(MyClass&& other) noexcept {
        if (this != &other) {
            delete data;
            data = other.data;
            other.data = nullptr;
        }
        return *this;
    }
};
```

**Move semantics:**
- Transfer resources instead of copying.
- `&&` — rvalue reference.
- `std::move()` — cast to rvalue.
- `noexcept` — important for optimizations.

C++: What is the Rule of Five in C++?