/////////////////////////////////////////////////////////////////////
// MT1Q8andMT4Q6.cpp

#include <string>
#include <iostream>
#include <sstream>

class B 
{ 
public:
  B(std::string s) : s_(s) {}
  std::string& str() { return s_; }
  /* ... */ 
private: 
  std::string s_; 
};

class D : public B { 
public:
  D() : B(""), i_(0) {}
  D(const D& d);
  D& operator=(const D& d);
  int& value() { return i_; }
private: 
  int i_; 
};

D::D(const D& d) : B(d), i_(d.i_) {}

D& D::operator =(const D& d)
{
  if(this == &d) return *this;
  static_cast<B>(*this) = d;
  i_ = d.i_;
  return *this;
}

void main()
{
  std::cout << "\n  Creating an instance of D:";
  D d1;
  d1.str() = "a D type";
  d1.value() = 1;
  std::cout << "\n    " << d1.str() << " with value " << d1.value();

  std::cout << "\n  Creating a D and assigning previous instance to it:";
  D d2;
  d2 = d1;
  std::cout << "\n    " << d1.str() << " with value " << d1.value();

  std::cout << "\n  Creating an instance of D as a copy of previous instance:";
  D d3 = d2;
  std::cout << "\n    " << d1.str() << " with value " << d1.value();
  std::cout << "\n\n";
}

  Creating an instance of D:
    a D type with value 1
  Creating a D and assigning previous instance to it:
    a D type with value 1
  Creating an instance of D as a copy of previous instance:
    a D type with value 1