//daughterstruct.hpp
struct Daughter
{
    int** p_pa;
    int** p_pb;

    Daughter()
    {
    }

    Daughter(int** a, int** b)
    {
        p_pa = a;
        p_pb = b;
    }
};

//motherstruct.hpp
#include"daughterstruct.hpp"

struct Mother
{
    int* p_a;
    int* p_b;

    int num1;
    int num2;
    int num3;
    int num4;

    Daughter daughter;

    Mother()
    {
        daughter = Daughter(&p_a, &p_b);

        p_a = &num1;
        p_b = &num2;

        num1 = 22;
        num2 = 0;
        num3 = 65;
        num4= 100;
    }

    ~Mother()
    {
        p_a = NULL;
        p_b = NULL;
    }

    void swap()
    {
        p_a = &num3;
        p_b = &num4;
    }
};

//main.cpp
#include<iostream>
#include"motherstruct.hpp"

void main()
{
    Mother mom;
    std::cout << mom.num1 << std::endl;
    std::cout << *mom.p_a << std::endl;
    std::cout << **mom.daught.p_pa << std::endl;


    // mom.p_a is pointing to mom.num3, and   mom.daught.p_pa is pointing to mom.p_a
    mom.swap();

    std::cout<<mom.num3 << std::endl;
    std::cout<<*mom.p_a << std::endl;
    std::cout<<**mom.daught.p_pa << std::endl;

    /*
    std::cout << mom.num1 << std::endl;
    std::cout << *mom.p_a << std::endl;
    std::cout << *mom.daught.p_pa << std::endl;

    mom.swap();

    std::cout << mom.num1 << std::endl;
    std::cout << *mom.p_a << std::endl;
    std::cout << *mom.daught.p_pa << std::endl;
    */
}