php 正则表达式提取网页超级链接url的函数

function match_links($document) { 
preg_match_all("'</s*a/s.*?href/s*=/s*([/"/'])?(?(1)(.*?)//1|([^/s/>]+))[^>]*>?(.*?)</a>'isx",$document,$links); 
while(list($key,$val) = each($links[2])) { 
if(!empty($val)) 
$match['link'][] = $val; 
} 
while(list($key,$val) = each($links[3])) { 
if(!empty($val)) 
$match['link'][] = $val; 
} 
while(list($key,$val) = each($links[4])) { 
if(!empty($val)) 
$match['content'][] = $val; 
} 
while(list($key,$val) = each($links[0])) { 
if(!empty($val)) 
$match['all'][] = $val; 
} 
return $match; 
}

public string GetHref(string HtmlCode) 
{ 
string MatchVale = ""; 
string Reg = @"(h|H)(r|R)(e|E)(f|F) *= *('|"")?((/w|//|//|/.|:|-|_)+)('|""| *|>)?"; 
foreach (Match m in Regex.Matches(HtmlCode, Reg)) 
{ 
MatchVale += (m.Value).ToLower().Replace("href=", "").Trim() + "||"; 
} 
return MatchVale; 
}