Polymorphism Exercises

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  1. Share with your neighbor(s) what is polymorphism and why we would want to use it.
  2. Write a SHORT C++ program that has a polymorphic method named print() that prints out its class name. Clearly label (with C++ comments) each of the four essential ingredients for having a polymorphic method call:
    1. Inheritance
    2. Virtual method (base class)
    3. Virtual method overridden in derived class
    4. Pointer or reference of the base class type, but pointing to/referencing the derived class
  3. Can a constructor be virtual? Share your thoughts about this with your neighbor(s).
  4. Without compiling the code, determine what the output of the following main function will be. 
    #include <iostream>
using namespace std;

class Base {
public:
    Base() {}
    virtual void A() { cout << "Base A\n"; }
    void B() { cout << "Base B\n"; }
};

class One : public Base {
public:
    One() {}
    void A() { cout << "One A\n"; }
    void B() { cout << "One B\n"; }
};

class Two : public Base {
public:
    Two() {}
    void A() { cout << "Two A\n"; }
    void B() { cout << "Two B\n"; }
};

int main() {
    Base* base0 = new Base;
    Base* base1 = new One;
    Base* base2 = new Two;
    
    base0->A();
    base0->B();
    cout << endl;

    base1->A();
    base1->B();
    cout << endl;

    base2->A();
    base2->B();
    cout << endl;

    return 0;
}

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