using System;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        List<string> test = new List<string>(new string[] {

            "David", "Morgan", "Philip" });

        Console.WriteLine(test.AsDelimited(" => "));

        List<int> primes = new List<int>(new int[] {

            2, 3, 5, 7, 11, 13, 17 });

        Console.WriteLine(primes.AsDelimited(" , "));

    }

}

​

static class EnumerableExtensions

{

    public static string AsDelimited<T>(this List<T> obj, string delimiter)

    {

        List<string> items = new List<string>();

        foreach (T data in obj)

        {

            items.Add(data.ToString());

        }

​

        return String.Join(delimiter, items.ToArray());

    }

}