C#的textbox多行模式限制输入

private void AllCount()

{

    foreach (string num in txbAllWater.Lines)

    {

        x = Convert.ToDouble(num);

                

        if (x < 0)

         {

            lisBoxAllMoney.Items.Add("用水量：" + x + " 立方米，" + "用水量不可能小于0！");

        }

        else if (x >= 0 && x <= 22)

        {

            y = 1.9 * x + 0.9 * x * 0.9;

            lisBoxAllMoney.Items.Add("用水量：" + x + " 立方米，" + "应缴水费：" + y.ToString() + " 元");

        }

        /*else...*/

    }

}



private void txbAllWater_KeyPress(object sender, KeyPressEventArgs e)

{

     if ((e.KeyChar < 48 || e.KeyChar > 57) && e.KeyChar != 8 && e.KeyChar != 13 && e.KeyChar != 45 && e.KeyChar != 46)

     {

         e.Handled = true;

     }

}