using System;

using System.Collections;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Windows.Forms;



namespace WindowsFormsApplication4

{

    public partial class Form2 : Form

    {

        class Item

        {

            public int ID { get; set; }

            public string Name { get; set; }

            public double Value { get; set; }

            public DateTime UpdateDateTime { get; set; }

        }



        public Form2()

        {

            InitializeComponent();

        }



        private void Form2_Load(object sender, EventArgs e)

        {

            var list = new List<Item>();

            for (int i = 0; i < 20; i++)

            {

                list.Add(new Item()

                {

                    ID = i,

                    Name = "Name of " + i.ToString(),

                    Value = i,

                    UpdateDateTime = DateTime.Now

                });

            }

            dataGridView1.DataSource = list;

            List<Item> nlist = (List<Item>)dataGridView1.DataSource;

            var resultTable = ConvertToDataTable<List<Item>>(nlist);



            var resultList = ConvertToList<List<Item>>(resultTable);