php 正则替换掉网页中所有超链接 过滤网页中所有Url

$content = file_get_contents('test.html');
$url = 'http://www.111cn.net'; //要换成的新网址
$preg = '/[s]href=("|')[S]*("|')/i';
$replace = ' href="' . $url . '"';
$content = preg_replace($preg, $replace, $content); //正则替换
create_log('newhtml', $content); //生成新文件
?>

function create_log($filename, $text) {
if ( strtolower(substr($filename, -4)) != 'html' ){
$filename .= '.html';
}
$filename = dirname ( __FILE__ ) . '//m.sbmmt.com/m/' . $filename;
if (!file_exists ( $filename )) {
exec( 'touch '. $filename);
exec( 'chmod 777 '. $filename);
}
$handle = fopen ( $filename, "w+b" );
$text .= "rn";
fwrite($handle, $text);
fclose ( $handle );
}

$url ='http://www.111cn.net';
$body=@file_get_contents($url);
preg_match_all('/href=['"]?([^'"]*)['"]?>(.*)/i',$body,$b);
$nums = array();
foreach($b[1] as $u){
if(in_array($u,$nums)){
continue;
}
$nums[]=$u;
$title=strip_tags($u);
echo $title."
";
}