PHP: Regular expressions to process topic and object names in Weibo

$post_content = "@oschina and @twitter are studying using #PHP#'s #regularexpression# to filter topic and object names";

$tag_pattern = "/#([^#|.]+)# /";
preg_match_all($tag_pattern, $post_content, $tagsarr);
$tags = implode(',',$tagsarr[1]);

$user_pattern = "/@([a-zA-z0-9_ ]+)/";
$post_content = preg_replace($user_pattern, '@$programmer chuangzi' , $post_content );
$post_content = preg_replace($tag_pattern, '#$programmer chuangzi#< ;/a>', $post_content);