Prime Factors In C#

Question

I want to create a program in C# 2005 which calculates prime factors of a given input. i want to use the basic and simplest things, no need to create a method for it nor array things etc. just simple modulus. is there any code which fulfills what i desire?

here is the code for finding simple factors, i need this code to be modified to calculate prime factors

class Program
{
    static void Main(string[] args)
    {
        int a, b;
        Console.WriteLine("Please enter your integer: ");
        a = int.Parse(Console.ReadLine());
        for (b = 1; b <= a; b++)
        {
            if (a % b == 0)
            {
                Console.WriteLine(b + " is a factor of " + a);
            }
        }
        Console.ReadLine();



    }
}

Answer 1

int a, b;
Console.WriteLine("Please enter your integer: ");
a = int.Parse(Console.ReadLine());

for (b = 2; a > 1; b++)
    if (a % b == 0)
    {
        int x = 0;
        while (a % b == 0)
        {
            a /= b;
            x++;
        }
        Console.WriteLine($"{b} is a prime factor {x} times!");
    }
Console.WriteLine("Th-Th-Th-Th-Th-... That's all, folks!");

Answer 2

public static List<int> Generate(int number)
{
    var primes = new List<int>();

    for (int div = 2; div <= number; div++)
        while (number % div == 0)
        {
            primes.Add(div);
            number = number / div;
        }
    
    return primes;
}

If you want to learn steps of development you can watch video here.

Answer 3

You can go one better as the divisor can never be larger than the square root of the number.

 for(int div = 2; div <= Math.Sqrt(number); div++)