﻿ C++ Object-Oriented Programming: Circle class

# C++ Object-Oriented Programming: Circle class

## C++ Object oriented programming: Exercise-1 with Solution

Write a C++ program to implement a class called Circle that has private member variables for radius. Include member functions to calculate the circle's area and circumference.

Sample Solution:

C Code:

#include <iostream> // Include necessary header for input/output stream

#include <cmath> // Include necessary header for mathematical functions

const double PI = 3.14159; // Define the value of PI as a constant

class Circle { // Define a class named Circle
private:

public:
// Constructor to initialize the Circle object with a radius

// Member function to calculate the area of the circle
double calculateArea() {
return PI * pow(radius, 2); // Formula to calculate the area of a circle
}

// Member function to calculate the circumference of the circle
double calculateCircumference() {
return 2 * PI * radius; // Formula to calculate the circumference of a circle
}
};

int main() {
// Create a circle object
std::cout << "Input the radius of the circle: ";

// Calculate and display the area of the circle
double area = circle.calculateArea(); // Calculate the area using the Circle object
std::cout << "Area: " << area << std::endl; // Output the calculated area

// Calculate and display the circumference of the circle
double circumference = circle.calculateCircumference(); // Calculate the circumference using the Circle object
std::cout << "Circumference: " << circumference << std::endl; // Output the calculated circumference

return 0; // Return 0 to indicate successful completion
}

Sample Output:

Input the radius of the circle: 5.2
Area: 84.9486
Circumference: 32.6725
Input the radius of the circle: 4
Area: 50.2654
Circumference: 25.1327

Explanation:

In the above exercise,

• const double PI = 3.14159;: This code defines a constant variable PI and assigns it the value of pi (approximately 3.14159).
• class Circle { ... }: This block defines a class named Circle. It has a private member variable radius to store the circle radius.
• Circle(double rad) : radius(rad) { }: This is the constructor of the Circle class. It takes a parameter rad and initializes the radius member variable with the given value.
• double calculateArea() { ... }: This member function calculates the circle area using the formula PI * radius^2. It returns the calculated area.
• double calculateCircumference() { ... }: This member function calculates the circumference of the circle using the formula 2 * PI * radius. It returns the calculated circumference.
• In the main() function, the program prompts the user to input the circle radius using std::cout and std::cin. It creates a Circle object by calling the constructor with the input radius.
• It then calls the calculateArea() and calculateCircumference() member functions on the Circle object to compute the area and circumference.

Flowchart:

CPP Code Editor: