qint.cpp

/*
 *  Copyright (C) 2020-2021 Andi Zhang <me@andi.ac>
 */

#include <iostream>

using namespace std;

class MyInt {
public:
    int val;
    int* bindInt;

    MyInt(int val, int* bindInt) {
        this -> val = val;
        this -> bindInt = bindInt;
        if(this -> bindInt != NULL) 
            *(this -> bindInt) = -val;
    }
    void operator=(int val) {
        this -> val = val;
        if(this -> bindInt != NULL) 
            *(this -> bindInt) = -val;
    }
    friend ostream& operator<<(ostream& out, const MyInt& a) {
        out << a.val;
        return out;
    }
};

class DoubleInt {
public: 
    MyInt a = MyInt(0, NULL);
    MyInt b = MyInt(0, NULL);

    DoubleInt(int val = 0) {
        (this -> a).bindInt = &(this -> b).val;
        (this -> b).bindInt = &(this -> a).val;
        this -> a = val;
    }
};

int main() {
    DoubleInt ab = DoubleInt();
    MyInt &a = ab.a;
    MyInt &b = ab.b;

    a = 8;
    cout << "a: " <<  a << ", b: " << b << endl;
    b = 666;
    cout << "a: " <<  a << ", b: " << b << endl;
}