Accessing static Data Members

A class’s private and protected static members are normally accessed through the class’s public member functions or friends. A class’s static members exist even when no objects of that class exist. To access a public static class member when no objects of the class exist, simply prefix the class name and the scope resolution operator (::) to the name of the data member. For example, if our preceding variable martianCount is public, it can be accessed with the expression Martian::martianCount, even when there are no Martian objects. (Of course, using public data is discouraged.)

To access a private or protected static class member when no objects of the class exist, provide a public static member function and call the function by prefixing its name with the class name and scope resolution operator. A static member function is a service of the class, not of a specific object of the class.