10. Static member function example

• 
  // point.h
  class Point
  {
      static int x_origin;
      static int y_origin;
      static void set_origin( int xx, int yy );
      //...
  };
  
  // point.cpp
  void Point::set_origin( int xx, int yy )
  {
      x_origin = xx;
      y_origin = yy;
  }