wordpress获取调用注册会员发表的文章数量

/* number of author's posts by zwwooooo */
 function num_of_author_posts($authorID=''){ //根据作者ID获取该作者的文章数量
     if ($authorID) {
         $author_query = new WP_Query( 'posts_per_page=-1&author='.$authorID );
         $i=0;
         while ($author_query->have_posts()) : $author_query->the_post(); ++$i; endwhile; wp_reset_postdata();
         return $i;
     }
     return false;
 }

global $wpdb
$users = $wpdb->get_var("select count(id) from $wpdb->users");
echo "总共有 ".$users." 位注册用户";