# Prime Number in C#

Published on 28 April 2022 (Updated: 25 September 2022) Welcome to the Prime Number in C# page! Here, you'll find the source code for this program as well as a description of how the program works.

## Current Solution

``````using System;
using Math = System.Math;

namespace SamplePrograms
{
{
public static bool IsPrime(ulong x)
{
if (x <= 1)
return false;
if (x != 2 && x % 2 == 0)
return false;

for (ulong i = 3; i <= Convert.ToUInt64(Math.Sqrt(x)); i += 2)
{
if (x % i == 0)
return false;
}

return true;
}

public static void Main(string[] args)
{
try
{
var n = ulong.Parse(args);
if (n > 18446744073709551615) // Max of a ulong in C#
{
Console.WriteLine(string.Format("{0} is out of the reasonable bounds for calculation.", n));
Environment.Exit(1);
}
var result = IsPrime(n) ? "Prime" : "Composite";
Console.WriteLine(result);
}
catch
{
Console.WriteLine("Usage: please input a non-negative integer");
Environment.Exit(1);
}
}
}
}
``````

Prime Number in C# was written by:

• Parker Johansen

If you see anything you'd like to change or update, please consider contributing.

Note: The solution shown above is the current solution in the Sample Programs repository as of May 02 2019 11:43:38. The solution was first committed on Dec 30 2018 01:40:03. As a result, documentation below may be outdated.

## How to Implement the Solution

No 'How to Implement the Solution' section available. Please consider contributing.

## How to Run the Solution

No 'How to Run the Solution' section available. Please consider contributing.