private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
        {
            if ((e.KeyChar >= '0' && e.KeyChar <= '9') || (e.KeyChar >= 'A' && e.KeyChar <= 'Z') || (e.KeyChar >= 'a' && e.KeyChar <= 'z') || (e.KeyChar == 13))
            { e.Handled = false;
           
             }
            else
            { e.Handled = true;
            return;//將 Handled 設(shè)置為 true,，以取消 KeyPress 事件。添加Return直接退出到方法外部,，不使用的話,，繼續(xù)運(yùn)行下面的程序
            }

            MessageBox.Show(e.KeyChar.ToString());

        }