Lecture 4 - Slide 35 : 40
Friends - class Point - notational convenience

We may wish to use the notation Move(p, dx,dy) instead of p.Move(dx,dy)

point.h
Class Point - header file.
point.cc
Class Point - implementation - not important for this example.
prog.cc
The program including implementation of friend moving functions.
Which relative moving operation do we prefer? The move_relatively member, Move_relatively_1, or Move_relatively_2 ?