private void txtAllow_KeyPress(object sender, KeyPressEventArgs e)
{
e.Handled = true;
if (this.txtAllow.TextLength == 0)
{
if ((e.KeyChar > '0' && e.KeyChar <= '9') || e.KeyChar == 8)
{
MessageBox.Show("输入正确");
e.Handled = true;
}
}
if (!(Char.IsNumber(e.KeyChar) || e.KeyChar == '\b'))
{
e.Handled = false;
}
}