Check if a page is a parent or if it's a child page?

Question

Is it possible to check if a page is a parent or if it's a child page?

I have my pages set up like this:

-- Parent

---- Child page 1

---- Child page 2

etc.

I want to show a certain menu if it's a parent page and a different menu if it's on the child page.

I know I can do something like below but I want to make it a bit more dynamic without including specific page ID's.

<?php if ($post->post_parent == '100') { // if current page is child of page with page ID 100    // show image X  } ?> 

Answer 1

You can test if the post is a subpage like this:
*(from http://codex.wordpress.org/Conditional_Tags)*

<?php  global $post;     // if outside the loop  if ( is_page() && $post->post_parent ) {     // This is a subpage  } else {     // This is not a subpage } ?> 

Answer 2

I know this is an old question but I was searching for this same question and couldn't find a clear and simple answer until I came up with this one. My answer doesn't answer his explanation but it answers the main question which is what I was looking for.

This checks whether a page is a child or a parent and allows you to show, for example a sidebar menu, only on pages that are either a child or a parent and not on pages that do not have a parent nor children.

<?php     global $post;        $children = get_pages( array( 'child_of' => $post->ID ) );    if ( is_page() && ($post->post_parent || count( $children ) > 0  )) :  ?>