Quiz: Inheritance and Virtual Functions

5 questionsNo time limitPass: 60%+10 XP on first pass

Reuse classes with inheritance, access modes, constructor order, virtual functions and the vtable, pure virtual functions and abstract classes, and why destructors must be virtual.

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Question 1
What makes a C++ class abstract?
The keyword abstractHaving at least one pure virtual function (= 0)Having a private constructorHaving no members

Question 2

What does this print?

#include <iostream>
using namespace std;
struct A { virtual void hi() { cout << "A"; } virtual ~A() = default; };
struct B : A { void hi() override { cout << "B"; } };
int main() {
    A *p = new B();
    p->hi();
    delete p;
    return 0;
}

ABABError

Question 3
In what order do constructors run for a Derived object?
Base first, then DerivedDerived first, then BaseOnly DerivedRandom order
Question 4
Why should a polymorphic base class have a virtual destructor?
To make it fasterSo deleting through a base pointer also runs the derived destructorDestructors can't be virtualTo allow copying
Question 5
What does the override keyword do?
Makes a function virtual in the baseMakes the compiler check that the function really overrides a base virtual functionHides the base classDeletes the base function