C# Program to Find the Largest Prime Factor of a Number

This is a C# Program to check whether the given number is a prime number if so then display its largest factor.

This C# Program Checks Whether the Given Number is a Prime number if so then Display its Largest Facor.

Here first the number that is obtained is checked whether the number is prime or not and then the largest factor of it is displayed.

Here is source code of the C# Program to Check Whether the Given Number is a Prime number if so then Display its Largest Factor. The C# program is successfully compiled and executed with Microsoft Visual Studio. The program output is also shown below.

/*
 * C# Program to Check Whether the Given Number is a Prime number if so then 
 * Display its Largest Factor
 */
using System;
namespace example
{
    class prime
    {
        public static void Main()
        {
            Console.Write("Enter a Number : ");
            int num;
            num = Convert.ToInt32(Console.ReadLine());
            int k;
            k = 0;
            for (int i = 1; i <= num; i++)
            {
                if (num % i == 0)
                {
                    k++;
                }
            }
            if (k == 2)
            {
                Console.WriteLine("Entered Number is a Prime Number and " + 
                                  "the Largest Factor is {0}",num);
            }
            else
            {
                Console.WriteLine("Not a Prime Number");
            }
            Console.ReadLine();
        }
    }
}

This C# program we are reading a number using ‘num’ variable. Compute the modulus of the value of ‘num’ variable by the value of ‘i’ variable is equal to 0. If the condition is true, then execute the statement. Print the largest factor among the prime number.

 
Enter a Number : 23
Entered Number is a Prime Number and the Largest Factor is 23