What is the Rule of Zero?

Question

Accepted Answer

**Rule of Zero** — if a class manages no resources, declare no special member functions.

```cpp
// Rule of Zero — let compiler handle everything
class Person {
    std::string name;
    int age;
public:
    Person(std::string n, int a) : name(std::move(n)), age(a) {}
    // No destructor, copy/move ops — compiler generates correct ones
};

// Rule of Five — managing raw resource
class Buffer {
    char* data;
    size_t size;
public:
    Buffer(size_t s) : data(new char[s]), size(s) {}
    ~Buffer() { delete[] data; }
    Buffer(const Buffer&);
    Buffer& operator=(const Buffer&);
    Buffer(Buffer&&) noexcept;
    Buffer& operator=(Buffer&&) noexcept;
};

// Best: use RAII wrappers to get Rule of Zero
class BetterBuffer {
    std::vector<char> data;  // No manual management
public:
    BetterBuffer(size_t s) : data(s) {}
    // Compiler-generated ops are correct!
};
```

**Rule of thumb:**
- Use RAII wrappers → Rule of Zero.
- Raw resources → Rule of Five.

C++: What is the Rule of Zero?