Example program of virtual function in C++

virtual_function_example.cpp

#include <iostream>

struct A
{
    virtual void do_something() {}
    virtual void do_something2() { std::cerr << "In A\n"; }
};

struct B : public A
{
    void do_something() {}
    void do_something2() { std::cerr << "In B\n"; }
};

int main()
{
    A* a = new B();
    a->do_something2();
    
    return 0;
}

// When executed, this program will print:
// $ ./a.out
// In B