PHP 8 reference · Array Functions

PHP array_key_first() Function

Return the first key of an array without moving its internal pointer, or null for an empty array. Added in 7.3.

PHP 8 Since 7.3

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Syntax

array_key_first(array $array): int|string|null

Parameter	Description
`array`	The input array.

The first key, or null.

First keyTry it yourself

<?php
$scores = ["ann" => 90, "bob" => 72];
echo array_key_first($scores), "\n";
var_dump(array_key_first([]));

Output

ann
NULL

First valueTry it yourself

<?php
$list = [5 => "x", 9 => "y"];
echo $list[array_key_first($list)], "\n";

Output

Version	Change
PHP 7.3	Added

array_key_last() · Return the last key of an array without moving its internal pointer, or null for an empty array. Added in 7.3.
array_first() · Return the first value of an array, or null if it's empty, without touching the internal pointer. Added in PHP 8.5.
PHP Arrays · tutorial
PHP Array Functions · tutorial