// Error: la clase tiene destructor, pero la copia por defecto copia el puntero.
#include <cstddef>
#include <iostream>

class IntBuffer {
public:
    explicit IntBuffer(std::size_t size) : data_(new int[size]()), size_(size) {}
    ~IntBuffer() {
        delete[] data_;
    }
    int& at(std::size_t index) {
        return data_[index];
    }
    std::size_t size() const {
        return size_;
    }

private:
    int* data_;
    std::size_t size_;
};

int main() {
    IntBuffer a(3);
    a.at(0) = 10;
    IntBuffer b = a;
    b.at(0) = 99;
    std::cout << "a.at(0) = " << a.at(0) << "\n";
    return 0;
}