PHP | SplObjectStorage key() Function

The SplObjectStorage::key() function is an inbuilt function in PHP which is used to get the index of the currently pointing iterator. Syntax:

int SplObjectStorage::key()

Parameters: This function does not accept any parameter. Return Value: This function returns the index at which the iterator currently pointing. Below programs illustrate the SplObjectStorage::key() function in PHP: Program 1:

php

<?php

// Create an empty SplObjectStorage
$str = new SplObjectStorage();

$obj = new StdClass;

$str->attach($obj, "d1");

$str->rewind();

// Get current index
$index  = $str->key();

// Print Result
var_dump($index);
?>

Output:

int(0)

Program 2:

php

<?php

// Create an Empty SplObjectStorage
$str = new SplObjectStorage();

$obj1 = new StdClass;
$obj2 = new StdClass;
$obj3 = new StdClass;
$obj4 = new StdClass;

$str->attach($obj1, "GeeksforGeeks");
$str->attach($obj2, "GFG");
$str->attach($obj3);
$str->attach($obj4, "DSA");

$str->rewind();

// Iterate and print data on each index
while($str->valid()) {

    // Get index
    $index  = $str->key();
    $object = $str->current();
    $data   = $str->getInfo();

    var_dump($index, $data);
    $str->next();
}
?>

Output:

int(0)
string(12) "GeksforGeeks"
int(1)
string(3) "GFG"
int(2)
NULL
int(3)
string(3) "DSA"

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