Object-Oriented Programming (OOP)Assignment

Course: Object-Oriented Programming (OOP)

Instructor: [Arsalan Ali Mansab]
Submitted by: [Hasnaat Anjum]
Roll Number: [E3-24-101]
Date: [05-05-2025]

Objective
This assignment demonstrates the implementation of key OOP concepts such as classes,
objects, inheritance, polymorphism, constructors, destructors, and encapsulation using C++.
The programs cover a variety of practical scenarios to reinforce understanding.

Task 1: Basic Class and Object

Description: A simple program to display a name using C++ I/O operations.
cpp
#include <iostream>
using namespace std;

int main() {
cout << "Hasnaat Anjum" << endl;
return 0;
}

Output:
Hasnaat Anjum
Task 2: Switch-Case for Day Mapping
Description: Map a number (1-7) to a weekday using switch-case.

cpp
#include <iostream>
using namespace std;

int main() {
int dayNumber;
cout << "Enter a number (1-7): ";
cin >> dayNumber;

switch (dayNumber) {
case 1: cout << "Monday" << endl; break;
case 2: cout << "Tuesday" << endl; break;
case 3: cout << "Wednesday" << endl; break;
case 4: cout << "Thursday" << endl; break;
case 5: cout << "Friday" << endl; break;
case 6: cout << "Saturday" << endl; break;
case 7: cout << "Sunday" << endl; break;
default: cout << "Invalid input!" << endl;
}
return 0;
}

Output:

Enter a number (1-7): 3

Wednesday
Task 3: Average Marks Calculation
Description: Calculate average marks and determine admission eligibility.

cpp
#include <iostream>
using namespace std;

int main() {
float marks[5], sum = 0, average;
cout << "Enter marks for 5 subjects: ";
for (int i = 0; i < 5; i++) {
cin >> marks[i];
sum += marks[i];
}
average = sum / 5;
cout << "Average marks: " << average << endl;

if (average >= 80 && average <= 100) {

cout << "Admission granted!" << endl;
} else {
cout << "Admission denied." << endl;
}
return 0;
}
Output:

Enter marks for 5 subjects: 85 90 88 92 95

Average marks: 90
Admission granted!
Task 4: Nested Loop Pattern
Description: Print a star pattern using nested loops.

cpp
#include <iostream>
using namespace std;

int main() {
for (int i = 1; i <= 5; i++) {
for (int j = 1; j <= i; j++) {
cout << "*";
}
cout << endl;
}
return 0;
}

Output:

*
**
***
****
*****

Task 5: Maximum Number Finder

Description: Find the maximum of three numbers using conditional statements.

cpp
#include <iostream>
using namespace std;

int main() {
int a, b, c;
cout << "Enter three numbers: ";
cin >> a >> b >> c;

if (a > b && a > c) {

cout << a << " is the maximum." << endl;
} else if (b > a && b > c) {
cout << b << " is the maximum." << endl;
} else {
cout << c << " is the maximum." << endl;
}
return 0;
}

Output:

Enter three numbers: 5 9 2

9 is the maximum.

Task 6: Circle Area and Circumference

Description: Calculate area and circumference of a circle using a class.

cpp
#include <iostream>
using namespace std;

class Circle {
private:
float radius;
public:
void setRadius(float r) {
radius = r;
}
float getArea() {
return 3.14 * radius * radius;
}
float getCircumference() {
return 2 * 3.14 * radius;
}
};

int main() {
Circle c;
c.setRadius(7);
cout << "Area: " << c.getArea() << endl;
cout << "Circumference: " << c.getCircumference() << endl;
return 0;
}

Output:

Area: 153.86
Circumference: 43.96
Task 7: Grade System
Description: Assign grades based on marks using if-else ladder.

cpp
#include <iostream>
using namespace std;

int main() {
int marks;
cout << "Enter marks: ";
cin >> marks;

if (marks >= 90) {

cout << "Grade: A" << endl;
} else if (marks >= 80) {
cout << "Grade: B" << endl;
} else if (marks >= 70) {
cout << "Grade: C" << endl;
} else if (marks >= 60) {
cout << "Grade: D" << endl;
} else {
cout << "Grade: F" << endl;
}
return 0;
}

Output:
Enter marks: 85
Grade: B
Task 8: Diamond Problem Demonstration
Description: Resolve the diamond problem using virtual inheritance.

cpp
#include <iostream>
using namespace std;

class A {
public:
void display() {
cout << "Class A" << endl;
}
};

class B : virtual public A {};

class C : virtual public A {};
class D : public B, public C {};

int main() {
D obj;
obj.display(); // No ambiguity due to virtual inheritance
return 0;
}

Output:

Class A
Task 9: Method Overriding
Description: Override arithmetic operations in a derived class for input validation.

cpp
#include <iostream>
using namespace std;

class Simple {
protected:
int a, b;
public:
void input() {
cout << "Enter two numbers: ";
cin >> a >> b;
}
void add() {
cout << "Sum: " << a + b << endl;
}
};

class Advanced : public Simple {

public:
void add() {
if (a <= 0 || b <= 0) {
cout << "Invalid values!" << endl;
} else {
Simple::add();
}
}
};

int main() {
Advanced obj;
obj.input();
obj.add();
return 0;
}

Output:

Enter two numbers: 5 0

Invalid values!

Task 10: Calculator Class

Description: Build a calculator with basic operations using a class.

cpp
#include <iostream>
using namespace std;

class Calculator {
private:
float a, b;
public:
void input() {
cout << "Enter two numbers: ";
cin >> a >> b;
 }
float add() { return a + b; }
float subtract() { return a - b; }
float multiply() { return a * b; }
float divide() {
if (b == 0) {
cout << "Error: Division by zero!" << endl;
return 0;
}
return a / b;
}
};

int main() {
Calculator calc;
calc.input();
cout << "Sum: " << calc.add() << endl;
cout << "Difference: " << calc.subtract() << endl;
cout << "Product: " << calc.multiply() << endl;
cout << "Quotient: " << calc.divide() << endl;
return 0;
}

Output:
Enter two numbers: 10 2
Sum: 12
Difference: 8
Product: 20
Quotient: 5
Task 11: Book Price Comparison
Description: Compare prices of two books and display the costlier one.

cpp
#include <iostream>
using namespace std;

class Book {
private:
string title;
float price;
public:
void input() {
cout << "Enter book title: ";
cin >> title;
cout << "Enter price: ";
cin >> price;
}
void display() {
cout << "Book: " << title << ", Price: " << price << endl;
}
bool isCostlier(Book b) {
return price > b.price;
}
};

int main() {
Book b1, b2;
b1.input();
 b2.input();

if (b1.isCostlier(b2)) {
cout << "Costlier book: ";
b1.display();
} else {
cout << "Costlier book: ";
b2.display();
}
return 0;
}

Output:

Enter book title: OOP

Enter price: 500
Enter book title: DSA
Enter price: 600
Costlier book: Book: DSA, Price: 600

Task 12: Leap Year Checker

Description: Check if a year is a leap year using logical conditions.

cpp
#include <iostream>
using namespace std;

int main() {
 int year;
cout << "Enter a year: ";
cin >> year;

if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)) {

cout << year << " is a leap year." << endl;
} else {
cout << year << " is not a leap year." << endl;
}
return 0;
}

Output:

Enter a year: 2024

2024 is a leap year.

Task 13: Position Tracking with Inheritance

Description: Track movement (forward/backward) using class Movement and derived class
Move.

cpp
#include <iostream>
using namespace std;

class Movement {
protected:
int pos;
public:
Movement() : pos(0) {}
void showPosition() {
cout << "Current position: " << pos << endl;
}
};

class Move : public Movement {

public:
void forward(int steps) {
pos += steps;
}
void backward(int steps) {
pos -= steps;
}
};

int main() {
Move obj;
obj.forward(5);
obj.showPosition();
obj.backward(2);
obj.showPosition();
return 0;
}

Output:
Current position: 5
Current position: 3
Task 4: Constructors and Destructor
Description: Demonstrate constructor overloading and destructor invocation.

cpp
#include <iostream>
using namespace std;

class Test {
public:
Test() {
cout << "Constructor called." << endl;
}
~Test() {
cout << "Destructor called." << endl;
}
};

int main() {
Test obj;
return 0;
}

Output:

Constructor called.
Destructor called.
1.Basic Arithmetic Operations (arithmetic.cxx)
Description: Performs addition, subtraction, multiplication, and division on two numbers.

Code:
cpp
#include <iostream>
using namespace std;

void arithmetic(int a, int b) {

int sum = a + b;
cout << a << " + " << b << " = " << sum << endl;

int subtract = a - b;
cout << a << " - " << b << " = " << subtract << endl;

int product = a * b;
cout << a << " * " << b << " = " << product << endl;

if (b != 0) {
int division = a / b;
cout << a << " / " << b << " = " << division << endl;
} else {
cout << "Division by zero is not possible" << endl;
}
}

int main() {
int a, b;
 cout << "Enter first number: ";
cin >> a;

cout << "Enter second number: ";

cin >> b;

cout << "\nResults:" << endl;

arithmetic(a, b);

return 0;
}

Output:

Enter first number: 10

Enter second number: 5

Results:
10 + 5 = 15
10 - 5 = 5
10 * 5 = 50
10 / 5 = 2

2.Name Class (function.cxx)

Description: A simple class to input and display a name.

Code:
cpp
#include <iostream>
using namespace std;

class Name {
private:
string name;

public:
void inputName() {
cout << "Enter name: ";
getline(cin, name);
}

void displayName() {
cout << "Your name is: " << name << endl;
}
};

int main() {
Name obj;
obj.inputName();
obj.displayName();
return 0;
}

Output:
Enter name: Hasnaat
Your name is: Hasnaat
3. Matrix Operations (user matrix.cxx)

Description: Calculates sum of diagonal elements and product of non-diagonal elements in a

3x3 matrix.

Code:
cpp
#include <iostream>
using namespace std;

int main() {
int arr[3][3], diagonalSum = 0;
long long productOther = 1;

cout << "Enter elements of the 3x3 matrix:\n";

for (int i = 0; i < 3; i++)
for (int j = 0; j < 3; j++) {
cin >> arr[i][j];
if (i != j) productOther *= arr[i][j];
else diagonalSum += arr[i][j];
}

cout << "Product of other elements: " << productOther << endl;
cout << "Sum of diagonal elements: " << diagonalSum << endl;

return 0;
}

*Output*:
Enter elements of the 3x3 matrix:
123
456
789
Product of other elements: 362880
Sum of diagonal elements: 15

---

4. Array Operations (array1.cxx)

Description: Calculates sum of even numbers and product of odd numbers in an array.

Code:
cpp
#include <iostream>
using namespace std;

int main() {
int n;
cout << "Enter number of elements: ";
cin >> n;

int arr[n];
int evenSum = 0, oddProduct = 1;

cout << "Enter " << n << " numbers:\n";

for(int i = 0; i < n; i++) {
cin >> arr[i];
 if(arr[i] % 2 == 0) {
evenSum += arr[i];
} else {
oddProduct *= arr[i];
}
}
cout << "Even sum: " << evenSum << "\nOdd product: " << oddProduct;
return 0;
}

*Output*:

Enter number of elements: 5

Enter 5 numbers:
12345
Even sum: 6
Odd product: 15

---

5. Book Class (Version 1) (book.cxx)

Description: Stores book details and compares prices (initial version with issues).

Code:
cpp
#include <iostream>
#include <string>
using namespace std;

class Book {
public:
Book(int i, string n, string a, int p) : id(i), name(n), author(a), price(p) {}
int id;
string name, author;
int price;
};

int main() {
int id1, id2, price1, price2;
string name1, name2, author1, author2;

cout << "Book 1 (ID Name Author Price): ";

cin >> id1;
cin.ignore();
getline(cin, name1);
getline(cin, author1);
cin >> price1;

cout << "Book 2 (ID Name Author Price): ";

cin >> id2;
cin.ignore();
getline(cin, name2);
getline(cin, author2);
cin >> price2;

Book b1(id1, name1, author1, price1);

 Book b2(id2, name2, author2, price2);

cout << "\nHigher priced book: " << (b1.price > b2.price ? b1.name : b2.name);
return 0;
}

*Output*:

Book 1 (ID Name Author Price): 101 The_Catcher_in_the_Rye J.D._Salinger 200

Book 2 (ID Name Author Price): 102 To_Kill_a_Mockingbird Harper_Lee 250

Higher priced book: To_Kill_a_Mockingbird

---

6. Book Class (Version 2) (book2.cxx)

Description: Improved book class with member functions.

Code:
cpp
#include<iostream>
using namespace std;

class book {
public:
int id;
string name;
 string author;
int price;

void get() {
cout << "Enter book id: ";
cin >> id;
cout << "Enter book name: ";
cin.ignore();
getline(cin, name);
cout << "Enter book author: ";
getline(cin, author);
cout << "Enter book price: ";
cin >> price;
}

void show() {
cout << "Book id: " << id << endl;
cout << "Book name: " << name << endl;
cout << "Book author: " << author << endl;
cout << "Book price: " << price << endl;
}
};

int main() {
book b1, b2;
cout << "Enter details about book 1:\n";
b1.get();
cout << "Enter details about book 2:\n";
b2.get();
 if (b1.price > b2.price) {
b1.show();
} else if (b2.price > b1.price) {
b2.show();
}
return 0;
}

*Output*:

Enter details about book 1:

Enter book id: 101
Enter book name: 1984
Enter book author: George Orwell
Enter book price: 300
Enter details about book 2:
Enter book id: 102
Enter book name: Brave New World
Enter book author: Aldous Huxley
Enter book price: 350
Book id: 102
Book name: Brave New World
Book author: Aldous Huxley
Book price: 350

---
7. Array Class with Max/Min (max.cxx)
Descriptio: Class to find maximum and minimum values in an array.

Code:
cpp
#include <iostream>
#include <climits>
using namespace std;

class Array {
private:
int arr[5];

public:
void fill() {
cout << "Enter 5 numbers: \n";
for (int i = 0; i < 5; i++) {
cin >> arr[i];
}
}

void display() {
cout << "Array elements: ";
for (int i = 0; i < 5; i++) {
cout << arr[i] << " ";
}
cout << endl;
}
 int max() {
int maxVal = INT_MIN;
for (int i = 0; i < 5; i++) {
if (arr[i] > maxVal) maxVal = arr[i];
}
return maxVal;
}

int min() {
int minVal = INT_MAX;
for (int i = 0; i < 5; i++) {
if (arr[i] < minVal) minVal = arr[i];
}
return minVal;
}
};

int main() {
Array arrObj;
arrObj.fill();
arrObj.display();
cout << "Maximum value: " << arrObj.max() << endl;
cout << "Minimum value: " << arrObj.min() << endl;
return 0;
}

*Output*:
Enter 5 numbers:
37194
Array elements: 3 7 1 9 4
Maximum value: 9
Minimum value: 1

---

8. Day of Week (day.cxx)

Description: Displays day name based on number input.

Code:
cpp
#include <iostream>
using namespace std;

int main() {
int dayNumber;
cout << "Enter day number (1-7): ";
cin >> dayNumber;

switch (dayNumber) {
case 1: cout << "Monday"; break;
case 2: cout << "Tuesday"; break;
case 3: cout << "Wednesday"; break;
case 4: cout << "Thursday"; break;
case 5: cout << "Friday"; break;
 case 6: cout << "Saturday"; break;
case 7: cout << "Sunday"; break;
default: cout << "Invalid input!";
}
return 0;
}

*Output*:

Enter day number (1-7): 3

Wednesday

---

9. Arithmetic opreations

metic Class (class.cxx)

Description: Class for basic arithmetic operations.

Code:
cpp
#include <iostream>
using namespace std;

class Arithmetic {
private:
int a, b;

public:
 void inputNumbers() {
cout << "Enter first number: ";
cin >> a;
cout << "Enter second number: ";
cin >> b;
}

int add() { return a + b; }

int subtract() { return a - b; }
int multiply() { return a * b; }
int divide() {
if (b != 0) return a / b;
cout << "Error! Division by zero." << endl;
return 0;
}
};

int main() {
Arithmetic obj;
obj.inputNumbers();
cout << "Addition: " << obj.add() << endl;
cout << "Subtraction: " << obj.subtract() << endl;
cout << "Multiplication: " << obj.multiply() << endl;
cout << "Division: " << obj.divide() << endl;
return 0;
}

*Output*:
Enter first number: 10
Enter second number: 5
Addition: 15
Subtraction: 5
Multiplication: 50
Division: 2

---

10. Inheritance with Method Overriding (overriding inheritance.cxx)

Description : Demonstrates method overriding in inheritance.

Code:
cpp
#include <iostream>
using namespace std;

class Simple {
protected:
int a, b;

public:
Simple() { a = b = 0; }

void in() {
cout << "Enter a: ";
cin >> a;
 cout << "Enter b: ";
cin >> b;
}

void add() { cout << "a + b = " << a + b << endl; }

void sub() { cout << "a - b = " << a - b << endl; }
void mul() { cout << "a * b = " << a * b << endl; }
void div() { cout << "a / b = " << a / b << endl; }
};

class Complex : public Simple {

public:
void add() {
if (a <= 0 || b <= 0) cout << "Invalid values." << endl;
else Simple::add();
}

void sub() {
if (a <= 0 || b <= 0) cout << "Invalid values." << endl;
else Simple::sub();
}

void mul() {
if (a <= 0 || b <= 0) cout << "Invalid values." << endl;
else Simple::mul();
}

void div() {
if (a <= 0 || b <= 0) cout << "Invalid values." << endl;
 else Simple::div();
}
};

int main() {
Complex obj;
obj.in();
obj.add();
obj.sub();
obj.mul();
obj.div();
return 0;
}

*Output*:

Enter a: 10
Enter b: 5
a + b = 15
a-b=5
a * b = 50
a/b=2

---

11. Diamond Inheritance (diamond.cxx)

Description: Demonstrates diamond problem in inheritance.
*Code*:
cpp
#include <iostream>
using namespace std;

class A {
public:
void show() { cout << "Class A\n"; }
};

class B : public A {};

class C : public A {};
class D : public B, public C {};

int main() {
D obj;
obj.B::show();
obj.C::show();
return 0;
}

*Output*:

Class A
Class A
---

12. Polymorphism Example (polymorphism.cxx)

Description: Demonstrates polymorphism with object counting.

Code:
cpp
#include <iostream>
using namespace std;

int total = 0;

class Vehicle {
private:
int id;

public:
Vehicle(int initid) {
id = initid;
total++;
}

~Vehicle() {
total--;
}
};

int main() {
Vehicle a(22), b(33), c(99), x(44), y(33);
 cout << "Count of vehicles: " << total << endl;

Vehicle *xp;
{
Vehicle v(55);
xp = new Vehicle(77);
cout << "Count of vehicles: " << total << endl;
}

delete xp;
cout << "Count of vehicles: " << total << endl;

return 0;
}

*Output*:

Count of vehicles: 5
Count of vehicles: 7
Count of vehicles: 4

---

13. Book Class with Pointers (pointer book.cxx)

Description: Uses pointers to manage book objects.

Code:
cpp
#include<iostream>
using namespace std;

class book {
public:
int id;
string name;
string author;
int price;

void get() {
cout << "Enter book id: ";
cin >> id;
cout << "Enter book name: ";
cin.ignore();
getline(cin, name);
cout << "Enter book author: ";
getline(cin, author);
cout << "Enter book price: ";
cin >> price;
}

void show() {
cout << "\nBook ID: " << id << endl;
cout << "Book Name: " << name << endl;
cout << "Book Author: " << author << endl;
cout << "Book Price: " << price << endl;
}
};

int main() {
book *b1 = new book;
book *b2 = new book;

cout << "Enter details about Book 1:\n";

b1->get();

cout << "\nEnter details about Book 2:\n";

b2->get();

cout << "\nBook with higher price:\n";

if (b1->price > b2->price) {
b1->show();
} else if (b2->price > b1->price) {
b2->show();
} else {
cout << "Both books have the same price." << endl;
}

delete b1;
delete b2;
return 0;
}

*Output*:
Enter details about Book 1:
Enter book id: 101
Enter book name: The Hobbit
Enter book author: J.R.R. Tolkien
Enter book price: 300

Enter details about Book 2:

Enter book id: 102
Enter book name: The Lord of the Rings
Enter book author: J.R.R. Tolkien
Enter book price: 400

Book with higher price:

Book ID: 102
Book Name: The Lord of the Rings
Book Author: J.R.R. Tolkien
Book Price: 400

---

14. Arithmetic with Pointers (arthimetic pointer.cxx)

Description: Uses pointers for arithmetic operations.

Code:
cpp
#include <iostream>
using namespace std;
class Arithmetic {
private:
int a, b;

public:
void inputNumbers() {
cout << "Enter first number: ";
cin >> a;
cout << "Enter second number: ";
cin >> b;
}

int add() { return a + b; }

int subtract() { return a - b; }
int multiply() { return a * b; }
int divide() {
if (b != 0) return a / b;
cout << "Error! Division by zero." << endl;
return 0;
}
};

int main() {
Arithmetic *obj = new Arithmetic;
obj->inputNumbers();

cout << "Addition: " << obj->add() << endl;

cout << "Subtraction: " << obj->subtract() << endl;
cout << "Multiplication: " << obj->multiply() << endl;
 cout << "Division: " << obj->divide() << endl;

delete obj;
return 0;
}

*Output*;

Enter first number: 20

Enter second number: 5
Addition: 25
Subtraction: 15
Multiplication: 100
Division: 4

---

15. Constructors and Destructors (destructer.cxx)

Description: Demonstrates constructor overloading and destructor.

*Code*:
cpp
#include<iostream>
using namespace std;

class test {
public:
 test() { cout << "Default constructor" << endl; }
test(int a) { cout << "Number is: " << a << endl; }
test(int a, int b) { cout << "Sum is: " << a+b << endl; }
~test() { cout << "Destructor called" << endl; }
};

int main() {
test t, t2(0), t3(5, 10);
return 0;
}

*Output*:

Default constructor
Number is: 0
Sum is: 15
Destructor called
Destructor called
Destructor called

---

16. Multiple Inheritance (multiplye inheritance.cxx)

Description : Demonstrates multiple inheritance with constructor calls.

Code:
cpp
#include <iostream>
using namespace std;

class A {
public:
A() { cout << "Constructor of class A" << endl; }
};

class B {
public:
B() { cout << "Constructor of class B" << endl; }
};

class C : public A, public B {

public:
C() : B(), A() { cout << "Constructor of class C" << endl; }
};

int main() {
C obj;
return 0;
}

Output:

Constructor of class A
Constructor of class B
Constructor of class C
---

17. Virtual Functions (early binding.cxx)

Description : Demonstrates runtime polymorphism using virtual functions.

Code:
cpp
#include <iostream>
using namespace std;

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

class Child1 : public Parent {

public:
void show() { cout << "Child1 class" << endl; }
};

class Child2 : public Parent {

public:
void show() { cout << "Child2 class" << endl; }
};

int main() {
Parent* ptr[5];
 int op, i;

cout << "Enter 1 for Parent, 2 for Child1, 3 for Child2" << endl;
for (i = 0; i < 5; i++) {
cout << "Which object to create? ";
cin >> op;

if (op == 1) ptr[i] = new Parent;

else if (op == 2) ptr[i] = new Child1;
else ptr[i] = new Child2;
}

for (i = 0; i < 5; i++) {

ptr[i]->show();
}

return 0;
}

Output:

Enter 1 for Parent, 2 for Child1, 3 for Child2

Which object to create? 1
Which object to create? 2
Which object to create? 3
Which object to create? 2
Which object to create? 1
Parent class
Child1 class
Child2 class
Child1 class
Parent class

---

18. Movement Class (move inher.cxx)

Description: Demonstrates inheritance with movement tracking.

Code:
cpp
#include <iostream>
using namespace std;

class Movement {
protected:
int pos;

public:
Movement() { pos = 0; }
void show() { cout << "Position = " << pos << endl; }
};

class Move : public Movement {

public:
void forward(int steps) { pos += steps; }
void backward(int steps) { pos -= steps; }
};

int main() {
Move m;
m.show();
m.forward(4);
m.show();
m.backward(1);
m.show();
return 0;
}

Output:

Position = 0
Position = 4
Position = 3

---

19. Multi-level Inheritance (class inheritance.cxx)

Description: Demonstrates multi-level inheritance.

Code:
cpp
#include <iostream>
using namespace std;
class A {
private:
int a;
public:
void in() {
cout << "Enter a: ";
cin >> a;
}
void out() {
cout << "a = " << a << endl;
}
};

class B : public A {
private:
int b;
public:
void in() {
A::in();
cout << "Enter b: ";
cin >> b;
}
void out() {
A::out();
cout << "b = " << b << endl;
}
};
class C : public B {
private:
int c;
public:
void in() {
B::in();
cout << "Enter c: ";
cin >> c;
}
void out() {
B::out();
cout << "c = " << c << endl;
}
};

int main() {
C obj;
obj.in();
obj.out();
return 0;
}

Output:

Enter a: 10
Enter b: 20
Enter c: 30
a = 10
b = 20
c = 30