Question

Implement a circle class. Each object of this class will represent a circle accepting its radius value as of float. Evaluate an area() function which will calculate the area of circle.

Answer 1

#include <iostream>
using namespace std;
class Circle
{
    float radius;

public:
    // Constructor to initialize radius
    Circle(float r)
    {
        radius = r;
    }

    // Function to calculate area
    float area()
    {
        return 3.1416 * radius * radius;
    }
};

int main()
{
    float r;

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

    Circle c(r);   // Creating object

    cout << "Area of circle is: " << c.area();

    return 0;
}

Explanation:

• The class Circle has:
• A data member radius of type float.
• A constructor to accept radius value.
• A member function area() that calculates area using the formula:

Area = πr²

Example:

Input: → 5

Output: → Area of circle is: 78.54