19.4. Pointer to Class Member

A pointer to member is a pointer that can point to a nonstatic member of a class. Normally a pointer points to an object, but a pointer to member identifies a member of a class, not an object of that class. static class members are not part of any object, so no special syntax is needed to point to a static member. Pointers to static members are ordinary pointers.

The type of a pointer to member embodies both the type of a class and the type of a member of that class. We initialize such pointers to point to a specific member of a class without identifying an object to which that member belongs. When we use a pointer to member, we supply the object whose member we wish to use.

To explain pointers to members, we’ll use a version of the Screen class from § 7.3.1 (p. 271):

class Screen {
public:
    typedef std::string::size_type pos;
    char get_cursor() const { return contents[cursor]; }
    char get() const;
    char get(pos ht, pos wd) const;
private:
    std::string contents;
    pos cursor;
    pos height, width;
};