function stripBBCode($text_to_search) {
     $pattern = '|[[\/\!]*?[^\[\]]*?]|si';
     $replace = '';
     return preg_replace($pattern, $replace, $text_to_search);
    }
    $text_to_search = "[url=http://google.com]google[/url] is fine";
    echo stripBBCode($text_to_search);