Adding "Related Posts" code

Hello,

I was trying to add a piece of code in order to get a “related posts” feature without any plugin. I added the following code in content-extensions.php - on the single post content ONLY :

<div class="relatedposts">
<h3>Related posts</h3>
<?php
	$orig_post = $post;
	global $post;
	$tags = wp_get_post_tags($post->ID);
	
	if ($tags) {
	$tag_ids = array();
	foreach($tags as $individual_tag) $tag_ids[] = $individual_tag->term_id;
	$args=array(
	'tag__in' => $tag_ids,
	'post__not_in' => array($post->ID),
	'posts_per_page'=>4, // Number of related posts to display.
	'caller_get_posts'=>1
	);
	
	$my_query = new wp_query( $args );

	while( $my_query->have_posts() ) {
	$my_query->the_post();
	?>
	
	<div class="relatedthumb">
		<a rel="external" href="<? the_permalink()?>"><?php the_post_thumbnail(array(150,100)); ?><br />
		<?php the_title(); ?>
		</a>
	</div>
	
	<? }
	}
	$post = $orig_post;
	wp_reset_query();
	?>
</div>

This was added just after this code (line 595 in the original file) :

							<div class="tags">

								<?php echo $tag_list; ?>

							</div>

But every time, I get an error message and I don’t understand why. If I write only HTML code, then it works. This is the error I get :

Parse error: syntax error, unexpected ‘;’, expecting ‘)’ in /home/alexandro/alexterieur/wp-content/themes/travelify/library/structure/content-extensions.php on line 300

Any idea ? I followed this tutorial : http://www.hongkiat.com/blog/wordpress-related-posts-without-plugins/

Thanks for your help

This code is outdated and no longer work since WordPress 3.1. Make sure to use another tutorials or use some plugin instead.