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__ ) . '/' . $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."";
}