4. Separating declarations and definitions

• 
  ////////////////////////////////////////////////////////
  // point.h
  class Point
  {
  public:
      int x; // member variables
      int y;
      void adjust( int xx, int yx ); // member declaration
  };
  
  ////////////////////////////////////////////////////////
  // point.cpp
  #include "point.h"
  void Point::adjust( int xx, int yy ) // member definition
  {
      x += xx; // Note: access to member variables is easy
      y += yy;
  }