Let's come back to our class Point. Its interface starts with the public section where we define four methods. Two for each coordinate to set and get its value. The
set methods are only declared. Their actual functionality is still to be defined. The get methods have a function body: They are defined within the class or, in other
words, they are inlined methods.
This type of method definition is useful for small and simple bodies. It also improve performance, because bodies of inlined methods are “copied'' into the code
wherever a call to such a method takes place.
On the contrary, calls to the set methods would result in a ``real'' function call. We define these methods outside of the class declaration. This makes it necessary, to indicate to which class a method definition belongs to. For example, another class might just define a method setX() which is quite different from that of Point. We
must be able to define the scope of the definition; we therefore use the scope operator “::'‘.
Here we define method setX() (setY()) within the scope of class Point. The object apoint can use these methods to set and get information about itself: