key

(PHP 4, PHP 5, PHP 7, PHP 8)

keyFetch a key from an array

Description

key(array|object $array): int|string|null

key() returns the index element of the current array position.

Parameters

array

The array.

Return Values

The key() function simply returns the key of the array element that's currently being pointed to by the internal pointer. It does not move the pointer in any way. If the internal pointer points beyond the end of the elements list or the array is empty, key() returns null.

Changelog

Version Description
8.1.0 Calling this function on objects is deprecated. Either use get_mangled_object_vars() on the object first, or use ArrayIterator.

Examples

Example #1 key() example

<?php
$array
= array(
'fruit1' => 'apple',
'fruit2' => 'orange',
'fruit3' => 'grape',
'fruit4' => 'apple',
'fruit5' => 'apple');

// this cycle echoes all associative array
// key where value equals "apple"
while ($fruit_name = current($array)) {
if (
$fruit_name == 'apple') {
echo
key($array), "\n";
}
next($array);
}
?>

The above example will output:

fruit1
fruit4
fruit5

See Also

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