Pointers to Members

You may take a class member’s address and assign it to a pointer. An address for a member can be obtained by applying the operator & to a “fully qualified” class member name. A class member pointer can be stated using the::* operator with the class name.

For example,

#include<iostream>
using namespace std;
class A
{
public:
int m;
A( )
{
m = 5;
}
void show() { 
int a;
cout<<"a="<<a<<endl;
}
};
int main()
{
A a;
int A::*ip = &A::m; //pointer to data member
void (A::*pf)(void) = &A::show; //pointer to function
cout<<a.*ip<<endl;
(a.*pf)( ); // calling show() using pf
return 0;
}

Output:

We can define a pointer to the member m as follows: 

int A::* ip = &A:: m; 

In the above statement, A::* means “pointer-to-member of A class”. 

The phrase &A::m means the “address of the m member of A Class”