Types of inheritance in C++ - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of Single Inheritance Example

What is the output of this C++ code demonstrating single inheritance?

C++

#include <iostream>
using namespace std;

class Animal {
public:
    void sound() { cout << "Animal sound" << endl; }
};

class Dog : public Animal {
public:
    void sound() { cout << "Dog barks" << endl; }
};

int main() {
    Dog d;
    d.sound();
    return 0;
}

A Dog barks\nAnimal sound

B Dog barks

C Compilation error

D Animal sound

💡 Hint

Look at which class's sound() method is called by the Dog object.

The Dog class overrides the sound() method of Animal. When calling d.sound(), Dog's version runs, printing 'Dog barks'.

❓ Predict Output

intermediate

Output of Multiple Inheritance Example

What is the output of this C++ code demonstrating multiple inheritance?

C++

#include <iostream>
using namespace std;

class Printer {
public:
    void print() { cout << "Printing document" << endl; }
};

class Scanner {
public:
    void scan() { cout << "Scanning document" << endl; }
};

class Copier : public Printer, public Scanner {
};

int main() {
    Copier c;
    c.print();
    c.scan();
    return 0;
}

A Scanning document

B Compilation error due to ambiguity

C Printing document

D Printing document\nScanning document

💡 Hint

Copier inherits both Printer and Scanner, so it can call both methods.

Copier inherits print() from Printer and scan() from Scanner. Both methods are called successfully, printing both lines.

❓ Predict Output

advanced

Output of Multilevel Inheritance with Overriding

What is the output of this C++ code demonstrating multilevel inheritance and method overriding?

C++

#include <iostream>
using namespace std;

class Vehicle {
public:
    virtual void start() { cout << "Vehicle starts" << endl; }
};

class Car : public Vehicle {
public:
    void start() override { cout << "Car starts" << endl; }
};

class SportsCar : public Car {
public:
    void start() override { cout << "SportsCar starts quickly" << endl; }
};

int main() {
    Vehicle* v = new SportsCar();
    v->start();
    delete v;
    return 0;
}

A Vehicle starts

B Car starts

C SportsCar starts quickly

D Compilation error due to override

💡 Hint

Virtual functions allow the most derived class's method to run through base class pointer.

Because start() is virtual, calling v->start() where v points to SportsCar runs SportsCar's start(), printing 'SportsCar starts quickly'.

❓ Predict Output

advanced

Output of Hierarchical Inheritance with Method Calls

What is the output of this C++ code demonstrating hierarchical inheritance?

C++

#include <iostream>
using namespace std;

class Shape {
public:
    void draw() { cout << "Drawing shape" << endl; }
};

class Circle : public Shape {
public:
    void draw() { cout << "Drawing circle" << endl; }
};

class Square : public Shape {
public:
    void draw() { cout << "Drawing square" << endl; }
};

int main() {
    Circle c;
    Square s;
    c.draw();
    s.draw();
    return 0;
}

A Drawing circle\nDrawing square

B Drawing shape\nDrawing shape

C Drawing circle\nDrawing shape

D Compilation error due to draw() redefinition

💡 Hint

Each derived class has its own draw() method that hides the base class method.

Circle and Square override draw(). Calling draw() on their objects prints their own messages, not the base class's.

🧠 Conceptual

expert

Diamond Problem in Multiple Inheritance

In C++, what problem arises in multiple inheritance when two base classes inherit from the same grandparent class, and a derived class inherits from both base classes? What is the typical solution?

A Ambiguity in accessing grandparent members; solved by virtual inheritance

B Compilation error due to duplicate class names; solved by renaming classes

C Runtime error due to conflicting constructors; solved by deleting one base class

D No problem arises; multiple inheritance always works without issues

💡 Hint

Think about how many copies of the grandparent class exist in the derived class.

The diamond problem causes ambiguity because the derived class inherits two copies of the grandparent class. Virtual inheritance ensures only one shared copy exists, resolving ambiguity.