For us to be able to make a "true" copy of a class (with a different memory address), it has to have a copy constructor.

#include <iostream>
using namespace std;

class Copier {
    public:
        Copier(int x) {
            this -> x = x;
        }
        Copier(const Copier &obj) { // a copy constructor (it takes a reference to the whole "Copier" type as an argument)
            this -> x = obj.x;
        }
        ~Copier(){}
        int x;
};

int main() {
    int a = 10;
    int b = a;
    a = 40;
    cout << "a: " << a << endl;
    cout << "b: " << b << endl;
    
    cout << "--------" << endl;
    
    Copier obj(10);
    Copier obj2 = obj;
    obj.x = 40;
    cout << "obj.x: " << obj.x << endl;
    cout << "obj2.x: " << obj2.x << endl;
    
    return 0;
}