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(PHP 5 >= 5.3.0)

SplHeap::compareCompare elements in order to place them correctly in the heap while sifting up.


abstract protected int SplHeap::compare ( mixed $value1 , mixed $value2 )

Compare value1 with value2.


Throwing exceptions in SplHeap::compare can corrupt the Heap and place it in a blocked state. You can unblock it by calling SplHeap::recoverFromCorruption. However, some elements might not be placed correctly and it may hence break the heap-property.



The value of the first node being compared.


The value of the second node being compared.

Return Values

Result of the comparison, positive integer if value1 is greater than value2, 0 if they are equal, negative integer otherwise.


Having multiple elements with the same value in a Heap is not recommended. They will end up in an arbitrary relative position.

PHP Manual