How to gain Access to member variables of a class using void pointer but Not Object

Question

I am trying to access member variables of a class without using object. please let me know how to go about.

class TestMem
{
    int a;
    int b;
public:
    Tes         


        

Answer 1

There totally is a way. C++ has member pointers, pointers relative to an object. They are defined by prefixing T:: to the * on the pointer type, and used by using the ->* or .* member pointer access operators. So yeah, it looks horrible :).

class T {
    int a, b;
public:
    typedef int T::* T_mem_ptr_to_int;

    static T_mem_ptr_to_int const a_ptr;
    static T_mem_ptr_to_int const b_ptr;
};

T::T_mem_ptr_to_int const T::a_ptr = &T::a;
T::T_mem_ptr_to_int const T::b_ptr = &T::b;

int weird_add(T* left, T* right) {
    return left->*T::a_ptr + right->*T::b_ptr;
}

This is used much more often for member function pointers, which look like Result (T::*ptr_name)(Arg1, Arg2, ...).