Example: How to Find Area of a Circle with Diameter in C++ using Constructor

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

class Area {
public:
    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
    Area(float x) {
        d = (2 * x);
        c = (2 * 3.14 * x);
        a = 3.14 * (x * x);
    }

    // It will produce the final output
    void 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;

    // It will create the instance of the `Area` class
    Area AR(r);

    AR.Output();
    return 0;
}