get previous/next post links

snippet-next-prev-post-links.php

<?php
				/**
				* Infinite next and previous post looping in WordPress
				*/

				$next_post = get_next_post();
				$previous_post = get_previous_post();
				$current_id = get_the_ID();

				// Get ID's of posts
				$next_id = $next_post->ID;
				$previous_id = $previous_post->ID;

				// get the first posts ID etc
				$args = array('post_type'=>'products', 'posts_per_page' => -1);
				$posts = get_posts($args);
				$first_id = $posts[0]->ID;

				// get the last posts ID etc
				$last_post = end($posts);
				$last_id =  $last_post->ID; // To get ID of last post in custom post type outside of loop

				if($previous_id) {
					$prev_post_url = get_permalink($previous_id);
				} else {
					$prev_post_url = get_permalink($first_id);

				};

				if($next_id) {
					$next_post_url = get_permalink($next_id);
				}  else {
					$next_post_url = get_permalink($last_id);
				} ?>

				<div class="wrapper paging">
					<a href="<?php echo $prev_post_url; ?>" class="prev-product"></a>
					<a href="<?php echo $next_post_url; ?>" class="next-product"></a>
				</div>