C++ Rule of zero

Rule of zero states that if a class manages resources correctly via RAII, it should define no special member functions at all—not destructor, copy constructor, copy assignment, move constructor, or move assignment. The compiler's defaults work correctly when members are themselves RAII-compliant (e.g., unique_ptr, vector, string).

Prefer the rule of zero by using standard library containers and smart pointers instead of manual resource management.

This example shows how using standard library types makes manual special members unnecessary.

// compile: g++ -o rule_zero rule_zero.cpp
// run: ./rule_zero
// description: rule of zero: no special members needed with standard containers
 
#include <iostream>
#include <vector>
#include <memory>
 
class Container {
private:
    std::vector<int> data;
    std::unique_ptr<int[]> buffer;
public:
    Container(size_t n) : buffer(std::make_unique<int[]>(n)) {}
 
    // No destructor, copy constructor, copy assignment, move constructor, or move assignment needed
    // Compiler-generated versions work correctly due to RAII members
};
 
int main() {
    Container c1(100);
    Container c2 = std::move(c1);  // move works correctly
    Container c3 = c2;              // copy works correctly
 
    return 0;
}