The Waite Group's C++ Primer Plus, Third Edition

Member Dereferencing Operators

Before discussing the member dereferencing operators, I must provide a bit of background. C++ lets you define pointers to members of a class, but the process is not simple. To see what's involved, let's look at a sample class that raises some problems:

class example
{
private:
    int feet;
    int inches;
public:
    example();
    example(int ft);
    ~example();
    void show_in();    // display inches member
    example operator+(example &ex);
};

Now suppose you want to define a pointer to the inches member of this class. The following attempt fails:

int * pi = &inches;    // not valid C++

It fails because inches is not type int. Because inches is declared in the class, it has class scope. Therefore, the type for inches must also specify ...