php匹配字符中链接地址程序代码

$str="ssdsf<a target='_blank' href='http://www.45it.net/' >sdf</a>sdfss";
if(preg_match("/<a/s+href=[^>]*>|<//[^a]*a[^>]*>/i",$str))
{
echo "该字符串有超链接";
}
else
{
echo "该字符串没有超链接标记";
}
?>

<?php
echo preg_replace("/(?<=href=)([^>]*)(?=>)/i","#", "<a href='www.45it.net'>你好，点这里看看</a><a href='www.45it.net'>你好，点这里看看</a>");
?>

function match_links($document) {   

    preg_match_all("'<s*as.*?hrefs*=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;

}