Empty 拡張メソッドで空のシーケンスを作成する

namespace Tips_Linq

{

    using System;

    using System.Linq;

    class Program

    {

        static void Main(string[] args)

        {

            var numbers = Enumerable.Empty<int>();

            var isOk = !numbers.Any();

            Console.WriteLine(isOk ? "空です。" : "空ではありません。");

            Console.ReadKey();

        }

    }

}

namespace Tips_Linq

{

    using System;

    using System.Collections.Generic;

    using System.Linq;

    class Program

    {

        static void Main(string[] args)

        {

            var numbers1 = new int[] { 1, 2, 3 };

            var numbers2 = new int[] { 1, 2, 3, 4, 5 };

            var numbers3 = new int[] { 4, 5 };

            var numbersList = new List<int[]>() { numbers1, numbers2, numbers3 };

            var list = numbersList.Aggregate(Enumerable.Empty<int>(), (current, next) => next.Count() > 2 ? current.Concat(next) : current);

            foreach (var number in list)

            {

                Console.WriteLine(number);

            }

            Console.ReadKey();

        }

    }

}