C# Program to Calculate the Area of a Circle

What is a Circle?

A circle is a round two-dimensional shape in which all the points on the surface of the circle are equal from a point known as the center. The distance between the center and any point on the boundary of a circle is known as the radius.

Area of a Circle

The area of a circle is the total area present inside the boundary of a circle. In this article, we are going to discuss different approaches on how we can calculate the area of a circle using C#.

The formula for the Area of the Circle: ? × r²

Where ? (pi) is approximately 3.14 or can be represented using Math.PI in C#.

r is the radius of the given circle.

Example

Input:
radius = 5 cm

Output:
Area = 78.54 cm²

Input:
radius = 10 cm

Output:
Area = 314.159 cm²

Input:
radius = 0 cm

Output:
Area = 0 cm²

Calculating Circle Area Using Direct Formula Approach

The area of the circle is calculated using the direct formula.

The formula for calculating the area of a circle if the radius is given: Area of Circle = ? × radius², where the value of ? is 3.14. After calculating the area of circle using the formula, we return the area of the circle.

Steps for Implementation

• We take radius as input.
• Use the formula for area = ? × radius².
• Return the calculated area.

Implementation Code

using System;

class Program
{
    static void Main()
    {
        double radius = 5;

        // area of the circle using the formula
        double area = Math.PI * Math.Pow(radius, 2);

        // Display the result
        Console.WriteLine($"The area of the circle with radius {radius} is: {area}");
    }
}

Output:

The area of the circle with radius 5 is: 78.5398163397448

Time Complexity: O(1)

Space Complexity: O(1)

Calculating Circle Area Using Function

We can use a function to calculate the area of a circle. The logic is the same, only we define another function. We define a function to calculate the area of the circle. We pass the radius as a parameter to the function. Finally, we return the calculated area from the function.

Steps for Implementation

• We first define a function to calculate the area of a circle.
• Now, pass the radius as an argument to the function.
• Return the calculated area from the function.

Implementation Code

using System;

class Program
{
    static double CalculateArea(double radius)
    {
        return Math.PI * Math.Pow(radius, 2);
    }

    static void Main()
    {
        double radius = 6;

        // Call the function
        double area = CalculateArea(radius);

        // Display the result
        Console.WriteLine($"The area of the circle with radius {radius} is: {area}");
    }
}

Output:

The area of the circle with radius 6 is: 113.09733552923255

Time Complexity: O(1)

Space Complexity: O(1)