正则 群组 Group

static void Main(string[] args)
{
string strUrl = "<a href=\"user.php?act=order_detail&order_id=425044\" target=\"_blank\" class=\"J_MakePoint status\">未付款</a> ";
var s=GetHTOrderId(strUrl);
//取到：order_id=425044
Console.Read();
}

private static string GetHTOrderId(string linkUrl)
{
string pattern = "<a href=\"user.php?(?<A>.+?)&(?<orderID>.+?)\".*>(?<B>.+?)</a>";
Regex rr = new Regex(pattern, RegexOptions.IgnoreCase);
MatchCollection matches = rr.Matches(linkUrl);

foreach (Match match in matches)
{
return match.Groups["orderID"].Value ;
}
return "";
}