// B10.cpp - implement a derived class assignment operator

#include <iostream>
using namespace std;

class A { 

  public:
    int& value() { return v; }
  private:
    int v;
};

class B {
  public:
    A& value() { return a; }
    void say() {
      cout << "\n  base value is " << a.value();
    }
  private:
    A a;
};
class D : public B {
  public:
  //// start of required answer ///////////
    D& operator=(const D &d) {
      if(this == &d) return *this;
      B::operator=(d);
      a = d.a;
      return *this;
    }
  //// end of required answer /////////////
    A& value() { return a; }
    A& baseValue() { return B::value(); }
    void say() {
      cout << "\n  derived value is " << a.value();
      B::say();
    }
  private:
    A a;
};

void main() {

  D d1;
  d1.value().value() = 1;
  d1.baseValue().value() = 2;
  d1.say();

  D d2;
  d2.value().value() = 3;
  d2.baseValue().value() = 4;
  d2.say();

  d2 = d1;
  d2.say();

  cout << "\n\n";
}