BCA 3rd Sem Top 20 Important Questions Object-Oriented Programming using C++ CCSU

1. Explain the term Class, Object, and Abstraction.

• Class: A blueprint for creating objects. It defines properties and methods.
• Object: An instance of a class that represents a real-world entity.
• Abstraction: Hiding implementation details and exposing only essential features.

---

2. Explain the term Data Hiding.

Data hiding ensures that internal object details (like private data members) are inaccessible directly, promoting encapsulation.

---

3. What is a Constructor?

A constructor is a special member function invoked automatically when an object is created. It initializes the object.

---

4. What is a Destructor?

A destructor is a special member function invoked automatically when an object is destroyed, used to release resources.

---

5. Difference Between Overloading and Overriding:

• Overloading: Same function name with different signatures.
• Overriding: Redefining a base class function in a derived class.

---

6. Difference Between OOP and POP:

• OOP: Focuses on objects and classes (e.g., inheritance, polymorphism).
• POP: Focuses on functions and procedures (e.g., structured programming).

---

7. Explain Generic Classes.

Generic classes use templates to define classes that work with any data type.

---

8. What is Inheritance & Types in C++?

Inheritance allows one class to derive properties and methods from another.
Types:

• Single
• Multiple
• Multilevel
• Hierarchical
• Hybrid

---

9. Differentiate Between << and >> Operators.

• <<: Used as the insertion operator (output).
• >>: Used as the extraction operator (input).

---

10. Define Encapsulation.

Encapsulation is bundling data and methods in a class, restricting direct access to some components.

---

11. Define Polymorphism and Its Types:

Polymorphism means "many forms."

• Compile-time: Function and operator overloading.
• Run-time: Virtual functions.

---

12. C++ Program for Fibonacci Series:

#include <iostream>
using namespace std;
int main() {
    int n1 = 0, n2 = 1, n3, count = 10;
    cout << n1 << " " << n2 << " ";
    for (int i = 2; i < count; ++i) {
        n3 = n1 + n2;
        cout << n3 << " ";
        n1 = n2;
        n2 = n3;
    }
    return 0;
}

---

13. C++ Program for Area Calculation Using Function Overloading:

#include <iostream>
using namespace std;
float area(float r) { return 3.14 * r * r; }  // Circle
float area(float l, float b) { return l * b; } // Rectangle
float area(float l, float b, float h) { return l * b * h; } // Cuboid
int main() {
    cout << "Area of Circle: " << area(5) << endl;
    cout << "Area of Rectangle: " << area(5, 10) << endl;
    cout << "Area of Cuboid: " << area(2, 3, 4) << endl;
    return 0;
}

---

14. Explain ifstream and ofstream for File I/O.

• ifstream: For reading files.
• ofstream: For writing files.

---

15. Exception Handling with Example:

#include <iostream>
using namespace std;
int main() {
    try {
        int x = 0;
        if (x == 0) throw "Divide by zero error!";
    } catch (const char* e) {
        cout << e << endl;
    }
    return 0;
}

---

16. Functions and Parameter Passing:

Functions are reusable blocks of code.
Parameter passing methods:

• Pass by Value
• Pass by Reference
• Pass by Pointer

---

17. Short Notes:

• Function Overloading: Defining multiple functions with the same name but different arguments.
• Operator Overloading: Redefining operators for user-defined types.
• Aggregation: A "has-a" relationship between objects.
• Exception Handling: Managing runtime errors using try, catch, and throw.
• Namespaces: Logical grouping of code to avoid naming conflicts.

---

18. Advantages of new & delete over malloc & calloc :-

• Automatic typecasting
• Constructors/destructors are called

---

19. Concept of Reusability:

Reusability allows code reuse via inheritance and modular design.

---

20. File Operations in C++:

• open: Open a file.
• read: Read data from a file.
• close: Close the file.
• eof: Check end-of-file.

---

If you need any further explanation or examples, let me know!

NOTE : 
This is an expected question answer which you have appeared in most of the exams. You will be able to study chapterwise most important topics as per your knowledge and will not be afraid of giving the paper. This is a great tool to improve your preparation.
The answers which are given in short cut or less words, here you can write and read them according to your understanding.