/** 
   cin >> val;  means that the method >> which is a member of the class
                specified by the left hand operand (in this case cin which
                is of type istream) is invoked with an actual parameter of 
                the type of the right hand operand.

  a + b;  means that the + method of the class associated with a is called 
          with a parameter of type b ( a.add(b) ). In order to use the a + b
          notation, I must define a function for the class of a that excepts
          a parameter of type b.
**/


#include <iostream.h>

class Myclass
{
  private:
    int val;
  public:
    Myclass(int o = 0) {val = o;}
    ~Myclass() {};
    Myclass add(Myclass a)
    {
      Myclass temp;

      temp.val = val + a.val;
      return(temp);
    }
    void output() {cout << val;}
    void input() {cin >> val;}
    Myclass operator + (Myclass a)
    {
      Myclass temp;

      temp.val = val + a.val;
      return(temp);
    }
};

int main(void)
{
  Myclass one, two;

  cout << 3 + 4;
  cout << "\nEnter an integer ";
  one.input();
  cout << "\none = ";
  one.output();
  two = one.add(one);
  cout << "\ntwo = ";
  two.output();

/** no operator "<<" matches these operands is the compiler error for the
    first line of code.  Similar messages are given for the other 2.  Since
    I want to be able to use these operators for my class instead of the
    more cumbersome one.add(), etc., I need some mechanism for defining
    the operators so that the operator (think function) has a version that
    uses the operands of the type I want.

  cout << one;
  cin >> two;
  two = one + one;
**/
/** after adding the operator + method to class Myclass **/
  two = one + one + one;
  cout << "\nNow two = ";
  two.output();
  cout << endl << endl;
  return(0);
}