The SplHeap::extract() function is an inbuilt function in PHP which is used to extract a node from top of the heap and sift up.

Generally, the Heap Data Structure are of two types:

• Max-Heap: In a Max-Heap, the key present at the root node must be greatest among the keys present at all of its children. The same property must be recursively true for all sub-trees in that Binary Tree.
• Min-Heap: In a Min-Heap, the key present at the root node must be minimum among the keys present at all of its children. The same property must be recursively true for all sub-trees in that Binary Tree.

Syntax:

mixed SplHeap::extract()

Parameters: This function does not accept any parameter.

Return Value: This function returns the value of the extracted node.

Below programs illustrate the SplHeap::extract() function in PHP:

Example 1:

<?php 

// Create a new empty Min Heap 
$heap = new SplMinHeap(); 

$heap->insert('System'); 
$heap->insert('GFG'); 
$heap->insert('ALGO'); 
$heap->insert('C');
$heap->insert('Geeks'); 
$heap->insert('GeeksforGeeks'); 

echo $heap->extract();

?>

Output:

ALGO

Example 2:

<?php 

// Create a new empty Max Heap 
$heap = new SplMaxHeap(); 

$heap->insert('System'); 
$heap->insert('GFG'); 
$heap->insert('ALGO'); 
$heap->insert('C');
$heap->insert('Geeks'); 
$heap->insert('GeeksforGeeks'); 

echo $heap->extract();

?>

Output:

System

Reference: https://www.php.net/manual/en/splheap.extract.php