PHP SplPriorityQueue key() Function

The SplPriorityQueue::key() function is an inbuilt function in PHP that is used to return the current node index.

Syntax:

mixed SplPriorityQueue::key()

Parameters: This function does not accept any parameter.

Return Value: This function returns the current node index.

Example:

PHP

<?php

// Declare a class
class priorityQueue extends SplPriorityQueue {

    // Compare function to compare priority
    // queue elements
    public function compare($p1, $p2) {
        if ($p1 === $p2) return 0;
        return $p1 < $p2 ? -1 : 1;
    }
}

// Create an object of priority queue
$obj = new priorityQueue();

// Insert elements into the queue
$obj->insert("Geeks",2);
$obj->insert("GFG",1);
$obj->insert("G4G",3);
$obj->insert('G',4);

// Use key() function to get the
// current key of priority queue
var_dump($obj->key());

?>

Output

int(3)

Reference: https://www.php.net/manual/en/splpriorityqueue.key.php