private void b_copy_select_Click(object sender, EventArgs e)
        {
            try
            {
                    bool checkedCell;
                    dataGridView2.Rows.Clear();

                    for (int i = 0; i < dataGridView1.RowCount; i++)
                    {
                        checkedCell = (bool)dataGridView1.Rows[i].Cells[4].Value;
                        if (checkedCell == true)
                        {
                            string f = dataGridView1.Rows[i].Cells[2].Value.ToString();
                            dataGridView2.Rows.Add(f);
                        }
                    }
            }

            catch { }

            try
            {
                    var newline = System.Environment.NewLine;
                    var clipboard_string = new StringBuilder();

                    for (int i2 = 0; i2 < dataGridView2.RowCount; i2++)
                    {
                        clipboard_string.Append(dataGridView2.Rows[i2].Cells[0].Value.ToString() + newline);
                    }
                    Clipboard.SetText(clipboard_string.ToString());
             }

            catch { }
        }