Example: How to Find Area of a Circle with Diameter in C++ using Class and Object

// How to Find Area of a Circle with Diameter in C++ using Class and Object
#include <bits/stdc++.h>
using namespace std;

class Calculation {
public:
    // This method will calculate the area of the circle
    void CalculateArea(float x) {
        float d = 0, c = 0, a = 0;
        // d is the diameter of the circle
        // c is the circumference of the circle
        // a is the area of the circle

        // It will calculate the diameter, circumference, and area of the circle
        d = (2 * x);
        c = (2 * 3.14 * x);
        a = 3.14 * (x * x);

        // It will produce the final output
        cout << "\n";
        cout << "Diameter      :: = " << d << " units\n";
        cout << "Circumference :: = " << c << " units\n";
        cout << "Area          :: = " << a << " sq. units\n";
    }
};

// It's the driver function
int main() {
    float r;  // radius of the circle

    cout << "Enter the radius of the circle::\n";
    cin >> r;

    // To make the instances of the `Calculation` class
    Calculation CA;

    CA.CalculateArea(r);
    return 0;
}