C# 配列やリストの値を結合する

using System;
using System.Collections.Generic;
using System.Linq;

namespace testapp
{
    class Program
    {

        static void Main(string[] args)
        {
            String[] str1 = new String[] { "h", "e" };
            String[] str2 = new String[] { "l", "l", "o" };

            List<int> list1 = new List<int> { 0, 1, 2 };
            List<int> list2 = new List<int> { 3, 4 };

            int[] arr = new int[] { 3, 4 };

            try
            {
                IEnumerable<String> result1 = str1.Concat(str2);
                IEnumerable<int> result2 = list1.Concat(list2);
                IEnumerable<int> result3 = list1.Concat(arr);

                Console.WriteLine($"実行結果は{String.Join(", ", result1.Select(v => v))}です");
                // h, e, l, l, o

                Console.WriteLine($"実行結果は{String.Join(", ", result2.Select(v => v))}です");
                // 0, 1, 2, 3, 4

                Console.WriteLine($"実行結果は{String.Join(", ", result3.Select(v => v))}です");
                // 0, 1, 2, 3, 4

            }
            catch (Exception e)
            {
                System.Console.WriteLine(e.ToString());
            }
        }
    }
}