using System;

using System.Linq;                  

public class Program

{

    public static void Main()

    {

        /*

         * This would be string userInput = Console.ReadLine();

         * Try changing one of the elements to a letter

         */

        string userInput = "1, 2, 3, 1, 2";

        var result = userInput.Strings();

        if (result.AllInt())

        {

            var intArray = result.ToIntegerArray();

            foreach (var intItem in intArray)

            {

                Console.WriteLine($"{intItem}");

            }

        }

        else

        {

            Console.WriteLine("One or more values can not represent an int");

        }

    }

}

​

public static class NumericArray

{

    /// <summary>

    /// Determine if each element in the string array can represent an int

    /// </summary>

    /// <param name="sender"></param>

    /// <returns></returns>

    public static bool AllInt(this string[] sender) =>

        sender.SelectMany(item => item.ToCharArray()).All(char.IsNumber);

​

    /// <summary>

    /// Convert a string array to an int array

    /// </summary>

    /// <param name="sender">string array which can represent integers</param>

    /// <returns>int array</returns>

    public static int[] ToIntegerArray(this string[] sender)

    {

​

        var intArray = Array

            .ConvertAll(sender,

                (input) => new

                {

                    IsInteger = int.TryParse(input, out var integerValue),

                    Value = integerValue

                })

            .Where(result => result.IsInteger)

            .Select(result => result.Value)

            .ToArray();

​

        return intArray;

​

    }

    /// <summary>

    /// Return a string array without spaces in elements

    /// </summary>

    /// <param name="sender"></param>

    /// <returns></returns>

    public static string[] Strings(this string sender, char separator = ',') 

        => sender.RemoveAllWhiteSpace().Split(separator);

​

    /// <summary>

    /// Remove all whitespace from a string

    /// </summary>

    /// <param name="sender"></param>

    /// <returns></returns>

    public static string RemoveAllWhiteSpace(this string sender)

        => sender

            .ToCharArray().Where(character => !char.IsWhiteSpace(character))

            .Select(c => c.ToString()).Aggregate((value1, value2) => value1 + value2);

}