Prime Numbers in C# Tutorial

Prime Number in C#:

Prime Numbers are the number which is not divisible by any number. Prime Numbers are Only Divisible by its own. 0 and 1 are not Prime Number as Prime Number starts from 2. Examples of Prime Numbers are 2, 3, 5, 7 ….

Prime number in C# can be calculated by various ways. We will calculate it by Using for loop.

Code:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace Prime_Number

{

    class Program

    {

        static void Main(string[] args)

        {

            Console.WriteLine("Enter number"); //Asking for the limit to which prime numbers will be calculated

            int upper_limit = Convert.ToInt32(Console.ReadLine());

            for (int i = 2; i < upper_limit; i++)  // Prime Number Starts from 2 so we are starting loop from 2 to upper limit

            {

                if (IsPrimeNumber(i) == true)  // Calling Prime Number Function whose data type is bool

                    Console.Write("{0}\t", i);

            }

        }

        static bool IsPrimeNumber(int number)  //   Parameter below upper limit

        {

            bool initial_Prime = true;    //   taking it as true initially

            int factor = number / 2;   // dividing the number which we want to check by 2

            int i;

            for (i = 2; i <= factor; i++)  // we will calculate remainder from 2 to half of the number

            {

                if ((number % i) == 0)   // if remainder is 0, then it can be divided by another number , hence not a prime number

                    initial_Prime = false;

            }

            return initial_Prime; 

        }

    }

}

Output:

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