密码必须是数字

 private void txtPwd_KeyPress(object sender, KeyPressEventArgs e)        {            if (e.KeyChar != 8 && !Char.IsDigit(e.KeyChar) && e.KeyChar != '.')            {                e.Handled = true;                MessageBox.Show("密码不符合要求，请您重新输入！","提示");            }            else                e.Handled = false;        }