course1_week4_challenge.cpp

// A base class Pair contains a single constructor Pair(a,b) that initializes the pair with the two integer arguments a and b. A derived class 
// sumPair inherits the base class Pair, and specializes it with a new constructor sumPair(a,b) and a new variable sum.

// Both of these classes have already been defined.

// Implement the new constructor sumPair(a,b), which was declared already in class sumPair. The new constructor sumPair(a,b) should initialize the 
// inherited class Pair with integer values a,b and set the member variable "sum" to the sum of a and b.

/* Class Pair has already been
 * declared and defined with the
 * following constructor:
 *
 *   Pair(int,int)
 *
 * that stores its two arguments in
 * two private member variables of Pair.
 *
 * Class sumPair has also already been
 * defined as follows:
 *
 * class sumPair : public Pair {
 * public:
 *   int sum;
 *   sumPair(int,int);
 * };
 * 
 * Implement the constructor
 * sumPair(int,int) such that it
 * loads the two member variables of
 * the base Pair class with its
 * arguments, and initializes the
 * member variable sum with their sum.
 */

sumPair::sumPair(int a, int b) : sum(a+b), Pair(a, b) {} // here order of initialization list does not matter

/* Below is a main() function
 * you can use to test your
 * implementation of the
 * sumPair constructor.
 */
 
int main() {
  sumPair sp(15,16);
  std::cout << "sp(15,16).sum =" << sp.sum << std::endl;
  return 0;
}