winform中TextBox只能输入字母

 private void txtTestPerson_KeyPress(object sender, KeyPressEventArgs e)
        {
         
            if ((e.KeyChar >= 'a' && e.KeyChar <= 'z') || (e.KeyChar >= 'A' && e.KeyChar <= 'Z') || e.KeyChar == '')
            {
                e.Handled = false;
            }
            else
            {
                e.Handled = true;
            }
        }