Pointers to member functions consists of the member function’s return type, the class name followed by ::, the pointer’s name, and the function’s parameter list. For example, a pointer to a member function of class A that returns int and takes no arguments is defined like this (note that both pairs of parentheses are mandatory):
class A { public: int func (); }; int (A::*pmf) (); /* pmf is a pointer to some member function of class A that returns int and takes no arguments*/In fact, a pointer to a member functions looks just like an ordinary pointer to function, except that it also contains the class's name immediately followed by the :: operator. You can invoke the member function to which pmf points like this:
pmf = &A::func; //assign pmf A a; A *pa = &a; (a.*pmf)(); // invoke a.func() // call through a pointer to an object (pa->*pmf)(); // calls pa->func()
Pointers to member functions respect polymorphism. Thus, if you call a virtual member function through a pointer to member, the call will be resolved dynamically:
class Base{ public: virtual int f (int n); }; class Derived : public Base { public: int f (int h); //override }; Base *pb = new Derived; int (Base::*pmf)(int) = &Base::f; (pb->*pmf)(5); // call resolved as D::f(5);
Note that you cannot take the address of a class's constructor(s) and destructor.
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