PHP | ArrayIterator key() Function

The ArrayIterator::key() function is an inbuilt function in PHP which returns the current key of the array element. Syntax:

mixed ArrayIterator::key( void )

Parameters: This function does not accept any parameters. Return Value: This function returns the current array key. Below programs illustrate the ArrayIterator::key() function in PHP: Program 1:

php

<?php
 
// Declare an ArrayIterator
$arrItr = new ArrayIterator(
    array('G', 'e', 'e', 'k', 's', 'f', 'o', 'r')
);

// Loop to display the array iterator key
foreach($arrItr as $element) {
    echo $arrItr->key() . "\n";
}
 
?>

Output:

0
1
2
3
4
5
6
7

Program 2:

php

<?php
 
// Declare an ArrayIterator
$arrItr = new ArrayIterator(
    array(
        "a" => "Geeks",
        "b" => "for",
        "c" => "Geeks"
    )
);
 
// Append the element into array iterator
$arrItr->append("Computer");
$arrItr->append("Science");
$arrItr->append("Portal");

// Display the key and its value of
// array iterator
foreach($arrItr as $element) {
    echo "key: " . $arrItr->key() . "  Value: "
            . $arrItr->current() . "\n";
}

?>

Output:

key: a  Value: Geeks
key: b  Value: for
key: c  Value: Geeks
key: 0  Value: Computer
key: 1  Value: Science
key: 2  Value: Portal

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

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