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!");
}

}