Why object-oriented programming is used in C++ - Challenge Your Understanding

Challenge - 5 Problems

🧠 Conceptual

intermediate

Main benefit of encapsulation in OOP

Which of the following best describes why encapsulation is used in object-oriented programming?

A To make all variables global for easy access

B To hide internal details and protect object data from outside interference

C To increase the speed of program execution

D To allow multiple inheritance from different classes

💡 Hint

Think about how OOP keeps data safe inside objects.

Encapsulation means bundling data and methods inside objects and restricting direct access to some components. This protects data integrity and hides complexity.

❓ Predict Output

intermediate

Output of inheritance example

What is the output of this C++ code using inheritance?

C++

#include <iostream>
using namespace std;

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

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

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

A Dog barks

B Animal speaks

C Compilation error due to speak() redefinition

D No output

💡 Hint

Which speak() method is called on the Dog object?

The Dog class has its own speak() method which overrides the Animal's speak(). So calling d.speak() prints "Dog barks".

❓ Predict Output

advanced

Output of polymorphism with virtual function

What is the output of this C++ code demonstrating polymorphism?

C++

#include <iostream>
using namespace std;

class Base {
public:
    virtual void show() { cout << "Base show" << endl; }
};

class Derived : public Base {
public:
    void show() override { cout << "Derived show" << endl; }
};

int main() {
    Base* b = new Derived();
    b->show();
    delete b;
    return 0;
}

A Base show

B Compilation error due to missing override keyword

C Derived show

D Runtime error due to invalid pointer

💡 Hint

Virtual functions allow calling the derived class method through base pointer.

Because show() is virtual, the call b->show() invokes Derived's show(), printing "Derived show".

🧠 Conceptual

advanced

Why use inheritance in OOP?

Which reason best explains why inheritance is used in object-oriented programming?

A To convert procedural code into assembly

B To make all functions static

C To prevent any changes to class behavior

D To reuse code and create a hierarchy of classes

💡 Hint

Think about how child classes relate to parent classes.

Inheritance allows new classes to reuse code from existing classes and organize them in a hierarchy, promoting code reuse and logical structure.

🧠 Conceptual

expert

Why is polymorphism important in OOP?

What is the main advantage of polymorphism in object-oriented programming?

A It allows objects of different classes to be treated through a common interface

B It forces all methods to have the same name

C It eliminates the need for constructors

D It makes programs run faster by skipping method calls

💡 Hint

Polymorphism helps with flexibility and code generalization.

Polymorphism lets different classes be accessed through the same interface, enabling flexible and extensible code.