Object Oriented Programming (OOP) — Pillars and Advantages: 19 MCQs with answers

A · It is based on objects that combine data and methods.

OOP is a paradigm based on the idea of objects, where data and methods are combined with each other, often modelled on real-life entities.

D · Kept separate, with functions emphasized.

Procedural programming keeps data and functions separate and emphasizes functions, unlike OOP which unites them in objects.

B · Compilation

The six pillars are Class, Object, Encapsulation, Abstraction, Inheritance, and Polymorphism. Compilation is not one of them.

B · A blueprint describing attributes and behaviours.

A class is the blueprint of the object; it cannot hold data directly and only describes attributes and behaviours.

D · Two objects of the class Car

Each car is an instance of the class Car, carrying the class's attributes with its own values — that makes them objects.

C · Private and protected

Encapsulation uses access modifiers such as private and protected to hide internal state and exposes functionality through public getter/setter methods.

D · Abstraction

Abstraction hides complex implementation details and shows only the essential features, focusing on what an object does rather than how.

A · True

OOP has six pillars: Class, Object, Encapsulation, Abstraction, Inheritance, and Polymorphism.

C · Encapsulation

The engine is hidden data and the pedal is the controlled access method — this is encapsulation, restricting direct access to internals.

B · Abstraction

The button is the abstraction: it hides complex implementation details and exposes only the essential feature to the user.

A · An 'is-a' relationship

Inheritance establishes an 'is-a' relationship — a sports car is a car — while promoting code reusability.

A · Polymorphism

Polymorphism means 'many forms' — the same interface (making a sound) expresses different behaviours across classes.

B · Encapsulation's maintainability

Encapsulation's maintainability advantage means external code remains unchanged even if the internal structure of the class changes.

B · Encapsulation → improved security

Improved security comes from encapsulation, which guards data by restricting direct access. Reusability comes from inheritance and reduced complexity from abstraction.

D · A is false but R is true.

The assertion is false — they are distinct pillars. The reason is true: encapsulation hides data (a mechanism) while abstraction hides complexity (a design decision).

A · The class cannot be used — encapsulation means choosing what to expose.

Encapsulation is about choosing what to expose, not hiding everything. A class with no public methods is useless; a class with everything public has no encapsulation.

C · Encapsulation

Encapsulation allows the internal data structure of a class to be changed without impacting external code that interacts with it, thereby ensuring maintainability.

D · Inheritance; it allows code reuse and extension

Inheritance is utilized here as `ElectricCar` inherits from `Car`, allowing it to reuse and extend the existing functionality while modifying specific behaviors, promoting code reusability.

C · Abstraction; it hides complex details from the user

Abstraction is exemplified here as it hides the complex implementation details of the remote control's operation, allowing users to interact with a simple interface while benefiting from reduced complexity.