派生クラスで基本クラスのコンストラクターと代入演算子を使用するにはどうすればよいですか?

<code class="cpp">class Base {
public:
    Base(const Base& b) { /*...*/ }
    Base& operator=(const Base& b) { /*...*/ }
};

class Derived : public Base {
public:
    Derived(const Derived& d)
        : Base(d), // Base constructor
          additional_(d.additional_) // Additional member initialization
    {
    }

    Derived& operator=(const Derived& d)
    {
        Base::operator=(d); // Base assignment operator
        additional_ = d.additional_;
        return *this;
    }
};</code>

<code class="cpp">class Base { 
    int value_;
};

class Derived : public Base {
public:
    Derived& operator=(const Derived& d)
    {
         Base::operator=(d); // Implicit invocation of base operator=
         // Perform derived-specific assignment
         return *this;
    }
};  </code>