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Program 1: Employee Class
cpp
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#include <iostream>
#include <string>
using namespace std;
class Employee {
private:
int empNo;
string empName;
float basic;
float da;
float it;
float netSalary;
public:
void getData() {
cout << "Enter Employee Number: ";
cin >> empNo;
cout << "Enter Employee Name: ";
cin.ignore();
getline(cin, empName);
cout << "Enter Basic Salary: ";
cin >> basic;
da = 0.52 * basic;
it = 0.3 * (basic + da);
netSalary = basic + da - it;
}
void displayData() {
cout << "nEmployee Details:n";
cout << "Employee Number: " << empNo << endl;
cout << "Employee Name: " << empName << endl;
cout << "Basic Salary: " << basic << endl;
cout << "DA: " << da << endl;
cout << "Income Tax: " << it << endl;
cout << "Net Salary: " << netSalary << endl;
}

};
int main() {
Employee emp;
emp.getData();
emp.displayData();
return 0;
}
Explanation:
1. #include <iostream> and #include <string>:
o Includes libraries for input/output operations (cin, cout) and
string handling (string).
2. using namespace std;:
o Avoids the need to prefix standard functions (e.g., std::cin).
3. class Employee:
o Defines a class Employee with private and public members.
o Private Members:
 empNo: Employee number.
 empName: Employee name.
 basic, da, it, netSalary: Basic salary, Dearness Allowance,
Income Tax, and Net Salary, respectively.
o Public Members:
 void getData():
 Prompts the user to input employee details.
 Calculates:
 da as 52% of basic.
 it as 30% of the sum of basic and da.
 netSalary as basic + da - it.
 void displayData():
 Displays the employee details, including computed
values (da, it, netSalary).
4. int main():
o Creates an object emp of the Employee class.
o Calls getData() to input details and displayData() to display the
results.
Program 2: Constructor Overloading
cpp
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#include <iostream>

class Box {
private:
double length, width, height;
public:
Box() {
length = width = height = 0;
}
Box(double l) {
length = width = height = l;
}
Box(double l, double w, double h) {
length = l;
width = w;
height = h;
}
double volume() {
return length * width * height;
}
void display() {
cout << "Volume: " << volume() << endl;
}
};
int main() {
Box b1;
Box b2(10);
Box b3(10, 20, 30);
cout << "Default Constructor: ";
b1.display();
cout << "Single Parameter: ";
b2.display();

cout << "Three Parameters: ";
b3.display();
return 0;
}
Explanation:
1. #include <iostream> and using namespace std;:
o Includes the library for input/output operations and uses the
standard namespace.
2. class Box:
o Defines a class to represent a 3D box with private data
members (length, width, height) and public methods.
o Constructors:
 Default Constructor:
 Initializes all dimensions (length, width, height) to
zero.
 Single Parameter Constructor:
 Initializes all dimensions to the same value (l).
 Parameterized Constructor:
 Initializes dimensions to specified values (l, w, h).
o Public Methods:
 double volume():
 Returns the volume of the box (length * width *
height).
 void display():
 Prints the calculated volume of the box.
3. int main():
o Creates three objects of Box:
 b1 using the default constructor.
 b2 using the single-parameter constructor.
 b3 using the three-parameter constructor.
o Calls the display() method for each object to show the volume.
Program 3: Multilevel Inheritance
cpp
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#include <iostream>
class Animal {

protected:
string species;
public:
void setSpecies(string s) {
species = s;
}
};
class Mammal : public Animal {
protected:
int legs;
public:
void setLegs(int l) {
legs = l;
}
};
class Dog : public Mammal {
private:
string breed;
public:
void setBreed(string b) {
breed = b;
}
void display() {
cout << "Species: " << species << endl;
cout << "Legs: " << legs << endl;
cout << "Breed: " << breed << endl;
}
};
int main() {
Dog dog;
dog.setSpecies("Canis");
dog.setLegs(4);

dog.setBreed("Labrador");
dog.display();
return 0;
}
Explanation:
standard namespace.
2. Multilevel Inheritance:
o class Animal:
 The base class with a protected member (species) and a
public method to set its value (setSpecies).
o class Mammal : public Animal:
 Inherits Animal and adds a protected member (legs) and a
method to set its value (setLegs).
o class Dog : public Mammal:
 Inherits Mammal and adds a private member (breed) and
a method to set its value (setBreed).
 void display():
 Displays the species, legs, and breed values.
3. int main():
o Creates an object dog of class Dog.
o Calls setSpecies, setLegs, and setBreed to set values for species,
number of legs, and breed.
o Calls display() to print the details.
Program 4: Array of Class Objects
cpp
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#include <iostream>
#include <string>
class Student {
private:
string name;
int rollNo;
char grade;
public:
void getData() {

cout << "Enter Name: ";
cin.ignore();
getline(cin, name);
cout << "Enter Roll Number: ";
cin >> rollNo;
cout << "Enter Grade: ";
cin >> grade;
}
void display() {
cout << "nName: " << name;
cout << "nRoll Number: " << rollNo;
cout << "nGrade: " << grade << endl;
}
};
int main() {
Student students[3];
for(int i = 0; i < 3; i++) {
cout << "nEnter details for student " << i+1 <<
":n";
students[i].getData();
}
cout << "nStudent Details:n";
for(int i = 0; i < 3; i++) {
students[i].display();
}
return 0;
}
Explanation:
1. #include <iostream> and #include <string>:
o Includes libraries for input/output operations and string
handling.
2. class Student:
o Represents a student with private data members (name, rollNo,
grade) and public methods.
o Public Methods:

 void getData():
 Prompts the user to input a students details and
stores them in private members.
 void display():
 Prints the stored student details.
3. int main():
o Creates an array students of size 3 to store details of three
students.
o Input Loop:
 Iterates over the array, calling getData() for each student.
o Output Loop:
 Iterates over the array, calling display() for each student
to print their details.
Program 5: Function Overloading for Shapes
cpp
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#include <iostream>
class Shape {
public:
double perimeter(double radius) {
return 2 * 3.14159 * radius;
}
double perimeter(double length, double width) {
return 2 * (length + width);
}
double perimeter(double a, double b, double c) {
return a + b + c;
}
};
int main() {
Shape shape;
cout << "Circle Perimeter: " << shape.perimeter(5) <<
endl;
cout << "Rectangle Perimeter: " << shape.perimeter(4, 6)
<< endl;

cout << "Triangle Perimeter: " << shape.perimeter(3, 4, 5)
<< endl;
return 0;
}
Explanation:
standard namespace.
2. class Shape:
o Represents a shape and contains three overloaded methods for
calculating the perimeter of different shapes.
o Method Overloading:
 perimeter(double radius): Calculates the perimeter of a
circle (2 * π * radius).
 perimeter(double length, double width): Calculates the
perimeter of a rectangle (2 * (length + width)).
 perimeter(double a, double b, double c): Calculates the
perimeter of a triangle (a + b + c).
3. int main():
o Creates an object shape of the Shape class.
o Calls each of the overloaded perimeter() methods to calculate
and display the perimeter of a circle, rectangle, and triangle.
Program 6: Constructor with Default Arguments
cpp
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#include <iostream>
class Rectangle {
private:
double length;
double width;
public:
Rectangle(double l = 1, double w = 1) {
length = l;
width = w;
}
void display() {

cout << "Length: " << length << ", Width: " <<
width << endl;
cout << "Area: " << length * width << endl;
}
};
int main() {
Rectangle r1;
Rectangle r2(5);
Rectangle r3(5, 10);
cout << "Default values: ";
r1.display();
cout << "One argument: ";
r2.display();
cout << "Two arguments: ";
r3.display();
return 0;
}
Explanation:
o Includes the input/output library for cin and cout operations.
2. class Rectangle:
o Represents a rectangle with private data members (length,
width).
o Constructor:
 The constructor accepts two arguments (l and w) with
default values (1), meaning if no arguments are passed,
both length and width will be initialized to 1.
o void display():
 Displays the dimensions (length, width) and the area
(length * width) of the rectangle.
3. int main():
o Creates three objects of the Rectangle class:
 r1 uses the default constructor with no arguments.
 r2 uses the constructor with one argument (5 for both
length and width).
 r3 uses the constructor with two arguments (5 and 10).
o Calls display() for each object to show their details.

Program 7: Bank Account Class
cpp
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#include <iostream>
class Account {
private:
double balance;
double interestRate;
public:
Account(double initial = 0, double rate = 0.05) {
balance = initial;
interestRate = rate;
}
void deposit(double amount) {
if(amount > 0) {
balance += amount;
cout << "Deposited: " << amount << endl;
}
}
void withdraw(double amount) {
if(amount <= balance) {
balance -= amount;
cout << "Withdrawn: " << amount << endl;
} else {
cout << "Insufficient funds" << endl;
}
}
void computeInterest() {
double interest = balance * interestRate;
balance += interest;
cout << "Interest added: " << interest << endl;
}

void showBalance() {
cout << "Current balance: " << balance << endl;
}
};
int main() {
Account acc(1000);
acc.showBalance();
acc.deposit(500);
acc.withdraw(200);
acc.computeInterest();
acc.showBalance();
return 0;
}
Explanation:
o Includes input/output functionality and the standard
namespace.
2. class Account:
o Represents a bank account with private members (balance and
interestRate).
o Constructor:
 Initializes balance with a default value of 0 and
interestRate with 0.05 (5%).
o Methods:
 void deposit(double amount):
 Deposits a positive amount into the account and
displays the deposited amount.
 void withdraw(double amount):
 Withdraws an amount if sufficient balance is
available. Displays an error message if insufficient
funds.
 void computeInterest():
 Computes and adds interest to the balance based
on interestRate.
 void showBalance():
 Displays the current balance.
3. int main():
o Creates an Account object acc with an initial balance of 1000.
o Calls methods to deposit, withdraw, compute interest, and
display the balance.

Program 8: Virtual Functions
cpp
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#include <iostream>
class Base {
public:
virtual void display() {
cout << "Base class display" << endl;
}
virtual void show() {
cout << "Base class show" << endl;
}
};
class Derived : public Base {
public:
void display() override {
cout << "Derived class display" << endl;
}
void show() override {
cout << "Derived class show" << endl;
}
};
int main() {
Base* base;
Derived derived;
base = &derived;
base->display();
base->show();
return 0;
}
Explanation:

o Includes the standard library for input/output operations.
2. class Base:
o Defines a base class with two virtual methods:
 virtual void display():
 A virtual method that can be overridden by derived
classes.
 virtual void show():
 Another virtual method.
3. class Derived : public Base:
o Inherits from Base and overrides both virtual methods.
o void display():
 Overridden method in the derived class.
o void show():
 Overridden method in the derived class.
4. int main():
o Creates a pointer base of type Base and an object derived of
type Derived.
o base = &derived;:
 The base pointer points to the derived object,
demonstrating polymorphism.
o Calls base->display() and base->show(), which invoke the
overridden methods in the Derived class due to virtual
functions.
5. Polymorphism:
o The use of virtual functions allows the derived class methods to
be called through a base class pointer, ensuring dynamic
dispatch.
Program 9: Friend Function
cpp
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#include <iostream>
class Complex {
private:
double real;
double imag;
public:
Complex(double r = 0, double i = 0) {

real = r;
imag = i;
}
friend Complex addComplex(Complex c1, Complex c2);
void display() {
cout << real << " + " << imag << "i" << endl;
}
};
Complex addComplex(Complex c1, Complex c2) {
Complex temp;
temp.real = c1.real + c2.real;
temp.imag = c1.imag + c2.imag;
return temp;
}
int main() {
Complex c1(3, 4), c2(5, 6);
Complex sum = addComplex(c1, c2);
cout << "First complex number: ";
c1.display();
cout << "Second complex number: ";
c2.display();
cout << "Sum: ";
sum.display();
return 0;
}
Explanation:
o Includes the necessary libraries for input/output operations.
2. class Complex:
o Represents a complex number with private members real and
imag.
o Constructor:
 Initializes the complex number with default values (0 for
both real and imag).

o Friend Function:
 friend Complex addComplex(Complex c1, Complex c2):
 This function is declared as a friend of the Complex
class, allowing it to access private members (real
and imag) directly.
 void display():
 Displays the complex number in the form real +
imag i.
3. Complex addComplex(Complex c1, Complex c2):
o Adds two complex numbers by adding their real and imaginary
parts separately.
4. int main():
o Creates two complex numbers c1 and c2.
o Uses the addComplex function to compute their sum and
displays the results.
Program 10: File Handling
cpp
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#include <iostream>
#include <fstream>
#include <string>
int main() {
ofstream outFile("sample.txt");
if(outFile.is_open()) {
outFile << "This is a line written to the file.n";
outFile << "This is another line.n";
outFile << "Adding some numbers: " << 42 << endl;
outFile.close();
cout << "File created and content written
successfully." << endl;
} else {
cout << "Unable to open file." << endl;
}
ifstream inFile("sample.txt");
string line;

cout << "nReading file contents:n";
if(inFile.is_open()) {
while(getline(inFile, line)) {
cout << line << endl;
}
inFile.close();
}
return 0;
}
Explanation:
1. #include <iostream>, #include <fstream>, and #include <string>:
o Includes the libraries for input/output operations, file handling
(fstream), and string manipulation.
2. ofstream outFile("sample.txt");:
o Creates an ofstream object to write data to a file named
sample.txt.
o if(outFile.is_open()):
 Checks if the file is successfully opened. If true, writes
lines to the file and closes it.
3. ifstream inFile("sample.txt");:
o Creates an ifstream object to read data from the file sample.txt.
o while(getline(inFile, line)):
 Reads the file line by line and prints each line.
4. File Operations:
o If the file cannot be opened, an error message is printed.
o After reading, the file is closed.

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