获取网页所有的url 正则

$index_page = file_get_contents('http://www.sina.com.cn');
$rule = '@<a.*?href=("|/'|)([^/'"#{};/s]+)("|/'|).*?>@ims';
preg_match_all($rule,$index_page,$out);
$all_index_urls = $out[2];
if(!empty($all_index_urls)){
foreach($all_index_urls as $k =>$url){
if(strpos($url,':void(') !== false){
unset($all_index_urls[$k]);
}
}
}
echo '<pre>';
print_r($all_index_urls);
echo '</pre>';