What will happen when I call a member function on a NULL object pointer?

Question

I was given the following as an interview question:

class A
{
public:
    void fun()
    {
        std::cout << "fun" << std::endl;
             


        

Answer 1

We can't know what will. Everything can happen, because the program exposes undefined behavior. See Does invoking a member function on a null instance cause undefined behavior?.