A reference to an object of a child class

child-reference.cpp

// A reference to an object of a child class

#include <iostream>

class A
{
public:
    virtual ~A() {}
    virtual void print() { std::cout << "A" << std::endl; }
};

class B: public A
{
public:
    void print() override { std::cout << "B" << std::endl; }
};

int main()
{
    A a;
    B b;
    A& a2 = b;
    A& a3 = a;
    
    a.print();
    b.print();
    a2.print();
    a3.print();
    
    a3 = b;
    a3.print();
}