Pointer to a member function

Why this post?

Code

// pointer to a member function
#include <iostream>

using namespace std;

class Dog
{
public:
void wag_tail() const
{
cout << "Tail left. Tail right. Wagging tail!" << endl;
}
void bark() const
{
cout << "Barrrrrrrrrrrk!" << endl;
}
};

int main()
{
Dog dog;
Dog * pdog = & dog;

void (Dog::*pfunc)() const = 0;
// point pfunc to wag_tail
pfunc = Dog::wag_tail;
(dog.*pfunc)();             // do NOT leave the first ()
(pdog->*pfunc)();           // do NOT leave the first ()
return 0;
}