Question

Given:

class Monster

{

    private:

    string name;

    int dangerLevel;

    public:

    Monster(sting, int);

    virtual void hunt() = 0;

    virtual void fight(Monster&);

    string getName() const;

};

class GiantMonster : public Monster

{

    protected:

        int height;

    

    public:

        GiantMonster(string, int, int);

        virtual void trample();

};

class Dinosaur : public GiantMonster

{

    public:

    Dinosaur(string, int, int);

    void hunt();

    void roar();

};

class Kraken : protected GiantMonster

{

    public:

    Kraken(string, int, int);

    virtual void hunt();

    void sinkShip();

};

Indicate if the code snippets below are valid or invalid:

a)

GiantMonster * m = new Kraken (“Sea Horror”, 500, 100);

b)

Kraken * k = new Kraken(“Cthulu”, 500, 100);

Cout << k->getName() << endl;

c)

Dinosaur trex(“T-Rex”, 100, 70);

GiantMonster m = trex;

m.roar();

d)

Monster * m = new GiantMonster (“Godzilla”, 100, 300);

e)

Dinosaur dino ( “Triceratops”, 0, 150);

Dinosaur trex ( “T-rex”, 200, 120);

Trex.fight(dino);

f)

Dinosaur * d = new Dinosaur (“T-Rex”, 100, 50);

GiantMonster * g = new Dinosaur (“Godzilla”, 100, 500);

g->fight(*d);

g)

Dinosaur * d = newGiantMonster(“T-Rex”, 100, 50);

Answer 1

a)

GiantMonster * m = new Kraken (“Sea Horror”, 500, 100);

This statement is invalid.
Because here base class is GiantMonster which is inaccessible.
So the conversion from Kraken to inaccessible base class GiantMonster is not allowed.

b)

Kraken * k = new Kraken(“Cthulu”, 500, 100);
Cout << k->getName() << endl;

This code snippet is invalid.
Because getName is in base class Monster. From GiantMonster getName is accessible. But Kraken can access only protected members of GiantMonster.
so for object k getName is inaccessible.

c)

Dinosaur trex(“T-Rex”, 100, 70);
GiantMonster m = trex;
m.roar();

This code snippet is invalid.
Because object of abstract class type "GiantMonster" is not allowed in c++.
Note :
GiantMonster is abstract class because this class has not Overriden(re-defined) "hunt" function from base class Monster.
hunt is a Pure Virtual Function and it needs to be implemented in GiantMonster.

Additionally to convert this snippet into valid one we need following code.
Dinosaur trex("T - Rex", 100, 70);
Dinosaur m = trex;
m.roar();

d)

Monster * m = new GiantMonster (“Godzilla”, 100, 300);
This code snippet is invalid.
Because object of abstract class type "GiantMonster" is not allowed in c++.

e)

Dinosaur dino ( “Triceratops”, 0, 150);
Dinosaur trex ( “T-rex”, 200, 120);
Trex.fight(dino);

I am not sure if there is a spelling mistake for 3rd line.
But if the statement at 3rd line is Trex.fight(dino); then the code snippet is invalid because variable names are case sensitive.
But if the statement at 3rd line is starts with small 't' i.e. trex.fight(dino); then the statement is valid.

f)

Dinosaur * d = new Dinosaur (“T-Rex”, 100, 50);
GiantMonster * g = new Dinosaur (“Godzilla”, 100, 500);
g->fight(*d);

This code snippet is valid.

g)

Dinosaur * d = newGiantMonster(“T-Rex”, 100, 50);
This code snippet is invalid.
Because object of abstract class type "GiantMonster" is not allowed in c++.