Quiz: Foundations of Object-Oriented Programming — 18 questions

1. What is the primary purpose of a programming language?

A. To write instructions that tell a computer how to perform tasks

B. To measure the electrical capacity of a computer processor

C. To translate spoken conversations into natural human languages

D. To organize hardware components into physical computer systems

Answer: (A)

Explanation

A programming language is used to write instructions that direct a computer to perform specific tasks. Organizing hardware, translating conversations, and measuring processor capacity are different functions.

2. Which sequence best illustrates procedural programming when making tea?

A. Store the ingredients as data while allowing functions to operate on them freely

B. Serve the tea, then decide whether to boil water based on its flavor

C. Boil water, add tea powder, add milk, add sugar, and serve

D. Create separate tea objects that independently control water and serving

Answer: (C)

Explanation

Procedural programming represents a task as an ordered sequence of steps, such as boiling water before adding ingredients and serving. The other choices describe nonsequential or object-centered approaches rather than a direct top-to-bottom procedure.

3. Which combination identifies major limitations of procedural programming in large software systems?

A. Flexible inheritance, controlled access, abstraction, and reduced code duplication

B. Clear object boundaries, reusable classes, hidden implementation details, and encapsulation

C. Poor reusability, difficult maintenance, dependent code, and weak data security

D. Automatic reuse, independent modules, strong data security, and simple maintenance

Answer: (C)

Explanation

Procedural programming can suffer from poor code reuse, dependent code, weak data security, and difficult maintenance as programs become large. The other choices describe advantages or mechanisms associated with object-oriented programming.

4. Why can error checking become difficult in a large procedural program?

A. Access control prevents functions from sharing data with related operations

B. Dependencies among procedures can make changes and faults spread across the program

C. Classes automatically hide implementation details from every procedure

D. Inheritance creates reusable methods that can be checked at several levels

Answer: (B)

Explanation

Large procedural programs may contain dependent code, so a change or fault in one procedure can affect other parts and complicate error checking. Classes, inheritance, and access control are object-oriented mechanisms rather than explanations of this procedural limitation.

5. What distinguishes object-oriented programming from procedural programming?

A. It focuses on executing one fixed series of steps to represent a real-world entity

B. It arranges instructions as a top-to-bottom sequence of independent procedures

C. It keeps data separate from the functions that process it in every design

D. It combines data and the functions operating on that data within objects

Answer: (D)

Explanation

Object-oriented programming combines data and related methods within objects that can represent real-world entities. A top-to-bottom sequence and separate data and functions characterize procedural programming instead.

6. A software team wants to reuse common features, restrict direct data access, and hide unnecessary implementation details; which object-oriented mechanisms address these goals?

A. Top-to-bottom execution, global data flow, and dependent procedures

B. Manual duplication, exposed implementation, and independent data records

C. Sequential instructions, separate functions, and unrestricted data sharing

D. Inheritance, access control, and abstraction or encapsulation

Answer: (D)

Explanation

Inheritance supports reuse, access control improves security, and abstraction and encapsulation hide details while controlling access. The other combinations describe procedural characteristics or practices that do not provide these object-oriented benefits.

7. What is the primary role of a class in object-oriented programming?

A. It represents a method call that selects code during execution

B. It stores one concrete entity with its current attribute values

C. It provides a blueprint containing data and functions for creating objects

D. It sends requests between existing objects to perform operations

Answer: (C)

Explanation

A class is a user-defined type and blueprint containing data members and member functions used to create objects. An object, rather than a class, is a concrete instance that occupies memory and holds actual values.

8. Which description best characterizes an object?

A. A variable declared inside a class to store one value

B. An identifiable instance of a class with state and behaviour

C. A logical template that declares attributes and methods

D. A code block inside a class that performs a specific task

Answer: (B)

Explanation

An object is an identifiable instance of a class that represents a real-world entity through its state and behaviour. A class defines possible attributes and methods but is not itself the concrete instance.

9. A student's name and marks describe the student's current state, while calculating an average describes what aspect of the object?

A. Its behaviour, expressed through methods or responses

B. Its class, which acts as the object's logical blueprint

C. Its identity, which determines the object's memory location

D. Its data members, which define the object's available actions

Answer: (A)

Explanation

An object's state is represented by its attributes, whereas its behaviour is represented by methods and responses to other objects. A calculation such as finding an average is an action performed through behaviour.

10. What does encapsulation accomplish in an object-oriented design?

A. It allows one operation to produce different behaviour in different situations

B. It displays essential information while concealing implementation details from users

C. It combines data with the functions operating on it and controls access through methods

D. It derives a new class from an existing class to reduce repeated code

Answer: (C)

Explanation

Encapsulation wraps data and the functions that operate on it into one unit, with access controlled through the unit's methods. Displaying essential information while hiding implementation details is the role of abstraction.

11. Which distinction correctly separates data abstraction from information hiding?

A. Abstraction combines data with methods, while information hiding creates subclasses for code reuse

B. Abstraction gives an operation several forms, while information hiding represents an object's state

C. Abstraction selects a method at runtime, while information hiding selects it during compilation

D. Abstraction hides implementation details, while information hiding protects sensitive data from unauthorized access

Answer: (D)

Explanation

Data abstraction presents essential information while concealing implementation details, whereas information hiding protects important or sensitive data from unauthorized access. Bundling data with methods describes encapsulation, not abstraction.

12. A new class reuses the properties and characteristics of an existing class to avoid duplicated code. Which OOP principle is being used?

A. Encapsulation

B. Inheritance

C. Information hiding

D. Polymorphism

Answer: (B)

Explanation

Inheritance allows a class to derive properties and characteristics from another class, promoting reuse and reducing duplication. Encapsulation concerns controlled bundling of data and its operating functions.

13. What does polymorphism allow an operation or message to do?

A. Keep data and its associated functions together inside one controlled unit

B. Appear in more than one form and produce different behaviour in different situations

C. Acquire properties and characteristics from a parent class

D. Reveal essential information while concealing implementation details

Answer: (B)

Explanation

Polymorphism is the ability of a message or operation to appear in multiple forms and produce different behaviour in different situations. Acquiring characteristics from another class is inheritance.

14. What is binding in object-oriented programming?

A. Combining an object's data with the functions that operate on it

B. Sending a request from one object to another to invoke a method

C. Associating a method call with the actual method or code that will execute

D. Representing an object's state through its attribute values

Answer: (C)

Explanation

Binding associates a method call with the actual method or code that will be executed. Sending a request between objects is message passing, which can eventually lead to a method call.

15. When a method call is linked to an implementation at compile time rather than during execution based on the actual object, what kind of binding is used?

A. Polymorphic binding, based on changing object state

B. Static binding, also called early binding

C. Message binding, based on a request between objects

D. Dynamic binding, also called late binding

Answer: (B)

Explanation

Static or early binding connects a method call to its implementation at compile time. Dynamic or late binding makes that connection at runtime according to the actual object.

16. What happens during message passing between objects?

A. A compiler connects every method call to its implementation before program execution

B. A subclass derives properties from a parent class to reduce code duplication

C. One object sends a request to another object to invoke a method and perform an operation

D. An object hides its implementation details while exposing essential information

Answer: (C)

Explanation

Message passing occurs when one object requests that another object invoke one of its methods to perform an operation. Compile-time method association describes static binding rather than message passing.

17. Which situation best demonstrates code reusability in object-oriented programming?

A. An object exposes its internal data directly to external procedures

B. A subclass uses an inherited method instead of rewriting its functionality

C. A developer changes several unrelated files after every small update

D. A program stores identical customer records in two separate databases

Answer: (B)

Explanation

Code reusability allows existing functionality to be used again through mechanisms such as inheritance, reusable classes, or methods. Storing duplicate records concerns data redundancy, while changing files concerns maintenance and exposing data conflicts with encapsulation.

18. How does encapsulation contribute to security in object-oriented programming?

A. It restricts unauthorized or accidental access to an object's data

B. It requires developers to rewrite dependent code after each modification

C. It lets every class reuse methods without defining access controls

D. It copies the same data into multiple storage locations for backup

Answer: (A)

Explanation

Encapsulation and data hiding protect an object's data from unauthorized or accidental access. Data duplication does not provide this protection, and reuse or maintenance addresses different benefits of object-oriented programming.