Explain C++ virtual dispatch and object lifetime

Answer the following C++ fundamentals questions.

1) Virtual function dispatch: predict output

Consider this C++ program:

#include <iostream>
using namespace std;

struct Base {
    Base() { cout << "Base()\n"; }
    virtual void vf() { cout << "Base::vf\n"; }
    void nvf() { cout << "Base::nvf\n"; }
    virtual ~Base() { cout << "~Base()\n"; }
};

struct Derived : Base {
    Derived() { cout << "Derived()\n"; }
    void vf() override { cout << "Derived::vf\n"; }
    void nvf() { cout << "Derived::nvf\n"; }
    ~Derived() override { cout << "~Derived()\n"; }
};

int main() {
    Base* p = new Derived();
    p->vf();
    p->nvf();
    delete p;
}

• What is the exact output (line by line)?
• Explain why each line prints (virtual dispatch vs non-virtual binding, and destructor behavior).

2) Destructors and dangling pointers

For each snippet below:

• identify whether it is correct, leaks memory, causes undefined behavior, or creates a dangling pointer;
• explain why;
• show a safer/fixed version.

(a)

int* make() {
    int x = 42;
    return &x;
}

(b)

int* p = new int(7);
delete p;
cout << *p << "\n";

(c)

int* p = new int(7);
int* q = p;
delete p;
delete q;

3) Pointer vs reference

Explain the differences between pointers and references in C++ (at least: nullability, reseating, ownership semantics, parameter passing, const behavior), and give examples of when you would choose each.