PHP Manual Function Reference Other Basic Extensions SPL Datastructures SplPriorityQueue SplPriorityQueue::key SplPriorityQueue::isEmpty SplPriorityQueue::next SplPriorityQueue::key (PHP 5 >= 5.3.0)SplPriorityQueue::key — Return current node index Description public mixed SplPriorityQueue::key ( void ) This function returns the current node index Parameters This function has no parameters. Return Values The current node index.