wordpress loop all posts and extract all links from content

$args = array(
  'post_type' => 'post',
);

$posts = get_posts($args);
foreach($posts as $post) {
  $content = $post->post_content;
  $regexp = '/(http|https|ftp|ftps)\:\/\/[a-zA-Z0-9\-\.]+\.[a-zA-Z]{2,3}(\/\S*)?/';
  preg_match_all($regexp, $content, $matches);
  $links = $matches[0];
}