Сохранение в текстовый документ - C#

        private void сохранитьToolStripMenuItem_Click(object sender, EventArgs e)
        {
            string str = "";
            SaveFileDialog sfd = new SaveFileDialog();
            if (sfd.ShowDialog() == DialogResult.OK)
            {
                StreamWriter streamWriter = new StreamWriter(sfd.FileName);
                for (int i = 0; i < 10; i++)
                    str += i + "\n";
                Console.Write(str);
                streamWriter.Write(str);
                streamWriter.Close();
            }
        }