How to find prime and non-prime numbers in an array with C#

1 Answer

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using System;

internal class Program
{
	public static bool isPrime(int num) {
		for (int i = 2; i <= num / 2; i++) {
			if (num % i == 0) {
				return false;
			}
		}
		return true;
	}

	public static void Main(string[] args)
	{
		int[] arr = new int[] {23, 87, 100, 47, 71, 897, 228, 3001, 4325, 8797, 5361};
		int size = arr.Length;

		for (int i = 0; i < size; i++) {
			if (isPrime(arr[i])) {
				Console.Write("{0,3:D} - Prime\n", arr[i]);
			}
			else {
				Console.Write("{0,3:D} - Not Prime\n", arr[i]);
			}
		}
	}
}



/*
run:
 
 23 - Prime
 87 - Not Prime
100 - Not Prime
 47 - Prime
 71 - Prime
897 - Not Prime
228 - Not Prime
3001 - Prime
4325 - Not Prime
8797 - Not Prime
5361 - Not Prime
 
*/

 



answered Feb 19, 2024 by avibootz
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