SplPriorityQueue::compare

(PHP 5 >= 5.3.0)

SplPriorityQueue::compare — Compare priorities in order to place elements correctly in the heap while sifting up.

int SplPriorityQueue::compare ( mixed $priority1 , mixed $priority2 )

Compare priority1 with priority2.

Result of the comparison, positive integer if priority1 is greater than priority2, 0 if they are equal, negative integer otherwise.

Замечание:
Multiple elements with the same priority will get dequeued in no particular order.