在single.php（單篇文章中）加入以下程式碼：
$cats = array();
foreach (get_the_category($post_id) as $c) {
$cat = get_category($c);
array_push($cats, $cat->slug);
}
if (sizeOf($cats) > 0) {
$post_categories = implode(',', $cats);
} else {
$post_categories = 'Not Assigned';
參考文章：https://developer.wordpress.org/reference/functions/get_the_category/
