how to add 50 value from textbox in array list fon button click

 private void button1_Click(object sender, EventArgs e)

        {

            ArrayList Ar = new ArrayList();

            foreach (Control ctl in this.Controls)

            {

                if (ctl is GroupBox)

                {

                    if (ctl.Name.ToString() == "GpB1")

                    {

                        foreach (Control ctl2 in ctl.Controls)

                        {

                            if (ctl2 is TextBox)

                            {

                                Ar.Add(ctl2.Text);

                            }

                        }

                    }

                }

            }

        }