The given PHP example is a function to get wordpress post/page slug to be used on for custom class etc. Code Example:
<?php
// Put in Functions.php
function the_slug(){
$post_data = get_post($post->ID, ARRAY_A);
$slug = $post_data['post_name'];
return $slug;
}
?>
<?php
// Put where you want to show in page or single etc. Use for custom class for each page
echo the_slug();
?>
