WIN TextBox限制只能输入数字

        private void t_KeyPress(object sender, KeyPressEventArgs e)
        {

            if (char.IsDigit(e.KeyChar) || e.KeyChar == (char)8)
            {
                return;
            }
            else
            {
                var txt = (TextBox)sender;
                var str = txt.Text.Insert(txt.SelectionStart,e.KeyChar.ToString() + "0");
                decimal d;
                if (!decimal.TryParse(str, out d))
                {
                    e.Handled = true;
                }
            }
        }