// CSE 374, 2015-03-04, BM

#include <iostream>

// class D will keep the default copy constructor
class D {
  public:
    int* z;

    D() {
      z = new int[4];
    }

    /* no redefinition of copy constructor.
     * C++ will give us the default, which
     * behaves the same as struct assignments.
     */
};

// class C will re-define the copy constructor
class C {
  public:
    int* z;

    C() {
      z = new int[4];
    }

    // re-define the copy constructor
    // to do a deep copy
    // QUIZ: copy constructor takes a reference, why not a value?
    // e.g. why C(C& to_copy) rather than C(C to_copy) ?
    C(C& to_copy) {
      std::cout << "copying" << std::endl;
      z = new int[4];
      for (int i=0; i<4; i++) {
        z[i] = to_copy.z[i];
      }
    }
};

// a function that takes an object of class C _by value_
void uses_c(C c) {
  std::cout << c.z << std::endl;
}

int main() {
  // calls constructor C()
  C c1;

  // calls the constructor C() 
  C c2;

  // calls the copy constructor on c2, with argument c1
  c2 = c1;  

  std::cout << "copied a C: " c1.z << " " << c2.z << std::endl;

  // calls copy constructor on c3, with argument c1
  C c3(c1);

  // since uses_c takes its argument by value,
  // c1 will be copied, invoking the copy constructor of C
  uses_c(c1);


  // demonstrate the default copy constructor
  D d1;
  D d2;
  d2 = d1;
  std::cout << "copied a D: " << d1.z << " " << d2.z << std::endl;
}