array_key_first()

array_key_first() — Gets the first key of an array.

Built-in function of PHP 8.5. The manual lists it as available in PHP 7 >= 7.3.0, PHP 8. This page is the reference card: signature, parameters and return value, plus the changelog and the example the manual provides.

What it does

Get the first key of the given array without affecting the internal array pointer.

Signature

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

Parameters

Return value

Returns the first key of array if the array is not empty; null otherwise.

Example

A runnable snippet:

$array = ['a' => 1, 'b' => 2, 'c' => 3]; $firstKey = array_key_first($array); var_dump($firstKey);

Output:

string(1) "a"

See also

array_first(), array_key_last(), reset()

All PHP 8.5 built-in functions

Reference card built from the PHP manual page array_key_first() (PHP documentation, CC BY 3.0). The page is generated from the manual, so the wording of the parameter and return value text follows php.net.