// version 5 - overload a simple class  
#include <iostream.h>
#include <iomanip.h>
#include <fstream.h>
#include <stdlib.h>

class Tclass{
friend ostream & operator << (ostream &, Tclass &);
private:
   int _x;
   int _y;
public:
   Tclass();
   Tclass (int, int);
   void show();
   void expand(int);
};
// quick implementation of class
Tclass::Tclass(): _x(10), _y(20) {};
Tclass::Tclass(int x, int y): _x(x), _y(y) {};
void Tclass::show() {
    cout << "{{ " << _x << ", " << _y  << "}}";
    }
void Tclass::expand(int factor) {
    _x *= factor;
    _y += factor;
    }

ostream&  operator << (ostream &Out, Tclass & T) {
    Out << "{{ " << T._x << ", " << T._y << "}}";
    return Out;
    }

main() {
  Tclass T(5, 10);

  T.show();
  cout << endl;
  cout << T << endl;

  fstream tout;
  tout.open("test5.txt", ios::out);
  if (!tout) {
     cerr <<"Can't open output file!" << endl;
     exit(1);
     }
  for (int z = 0; z < 3; ++z) {
     tout << T;
     T.expand(1+z);
     }
  tout.flush();
  tout.close();
}