C#------如何判断输入的是否为纯数字

private void Btn_OK_Click(object sender, EventArgs e)
        {
            IDormitoryAdminCardService aservice = new DormitoryAdminCardService();

            string text = this.CardNoEdit.Text;

            //判断是否输入的是纯数字
            string pattern = "^[0-9]*$";
            Regex regex = new Regex(pattern);

            if (regex.IsMatch(text))
            {
                aservice.AddCard(text);

                ShowSuccess("添加成功!");

                if (SaveEvent != null)
                {
                    SaveEvent(null, new EventArgs());
                }

                this.Close();
            }
            else
            {
                ShowError("请输入数字!");
            }

        }