using System;

using System.Linq;

public static class Extensions 

{

    public static void Add<T>(this T[] _self, T item)

    {

        Array.Resize(ref _self, _self.Length + 1);

        _self[_self.Length - 1] = item;

        //_self = _self.Concat(new T[] { item }).ToArray();

    }

}

public class Program

{

    public static void Main()

    {

        string[] test = { "Hello" };

        test = test.Concat(new string[] { "cruel" }).ToArray();

        test.Add("but funny");

        Console.WriteLine(String.Join(" ", test) + " world");

    }

}