Question

How to calculate the area, diameter, and circumference of a circle in C#

Answer 1

// Online C# compiler (editor) for free
// Write and run C# online using this editor.

using System;

public class Program {
    public static void Main(string[] args) {
        int radius = 3;
        float PI = 3.14f;
 
        float area = PI * radius * radius;
        Console.WriteLine("Area = {0:F2}", area);
 
        float diameter = 2 * radius;
        Console.WriteLine("Diameter = {0:F2}", diameter);
 
        float circumference = 2 * PI * radius;
        Console.WriteLine("Circumference = {0:F2}", circumference);
    }
}


/*
run:

Area = 28.26
Diameter = 6.00
Circumference = 18.84

*/

 

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Answer 2

using System;

namespace CircleCalculatorApp
{
    public class Program
    {
        public static void Main(string[] args)
        {
            try
            {
                double radius = 3.0;

                // Perform calculations using our utility functions
                double diameter = CalculateDiameter(radius);
                double circumference = CalculateCircumference(radius);
                double area = CalculateArea(radius);

                // Output results formatted to 2 decimal places
                Console.WriteLine($"Radius: {radius}");
                Console.WriteLine($"Diameter: {diameter}");
                Console.WriteLine($"Circumference: {circumference:F2}");
                Console.WriteLine($"Area: {area:F2}");
            }
            catch (ArgumentException ex)
            {
                Console.WriteLine($"Error: {ex.Message}");
            }
        }

        /// <summary>
        /// Calculates the diameter of a circle (Diameter = 2 * r).
        /// </summary>
        /// <param name="radius">The radius of the circle.</param>
        /// <returns>The calculated diameter.</returns>
        public static double CalculateDiameter(double radius)
        {
            ValidateRadius(radius);
            
            return 2 * radius;
        }

        /// <summary>
        /// Calculates the circumference of a circle (Circumference = 2 * pi * r).
        /// </summary>
        /// <param name="radius">The radius of the circle.</param>
        /// <returns>The calculated circumference.</returns>
        public static double CalculateCircumference(double radius)
        {
            ValidateRadius(radius);
            
            return 2 * Math.PI * radius;
        }

        /// <summary>
        /// Calculates the area of a circle (Area = pi * r^2).
        /// </summary>
        /// <param name="radius">The radius of the circle.</param>
        /// <returns>The calculated area.</returns>
        public static double CalculateArea(double radius)
        {
            ValidateRadius(radius);
            
            // Using multiplication (radius * radius) is more efficient than Math.Pow(radius, 2)
            return Math.PI * (radius * radius);
        }

        /// <summary>
        /// Validates that the radius is a non-negative number.
        /// </summary>
        private static void ValidateRadius(double radius)
        {
            if (radius < 0) {
                throw new ArgumentException("Radius cannot be negative.", nameof(radius));
            }
        }
    }
}


/*
run:

Radius: 3
Diameter: 6
Circumference: 18.85
Area: 28.27

*/

 

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