List Current Parent and Child Pages in WordPress

Recently in WordPress I needed to create a navigation that would display a page’s parent page and all of that pages children, I am a bit rusty with PHP but here is what I got to work.

<ul>
<?php
  if($post->post_parent == 0) {
    $pageLinkID = $post->ID;
    $title = $post->post_title;
  } else {
    $pageLinkID = $post->post_parent;
    $title = get_the_title($post->post_parent);
  }
  echo '<li class="parent"><a href="'.get_page_link($pageLinkID).'">'.$title.'</a></li>';
  $pages = get_pages('child_of='.$pageLinkID);
  foreach ($pages as $p) {
    echo '<li><a href="'.get_page_link($p->ID).'">'.$p->post_title.'</a></li>';
  }
?>
</ul>

If you need to order the posts by the order value change the

$pages = 

Line to

$pages = get_pages('child_of='.$pageLinkID.', 'sort_column' => 'menu_order', 'sort_order' => 'asc');