array_key_first

Function • Params and return types changed in PHP 8.0

Gets the first key of an array.

PHP 5
PHP 7.0-7.2
PHP 7.3
Added
PHP 7.4
PHP 8.0
Improved
PHP 8.1-8.2
PHP 8.3
PHP 8.4
PHP 8.5

array_key_first Function synopsis

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

Parameters

$array

Typearray

An array.

Return value

Typestring|int|null

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

Changes to the array_key_first Function

PHP 8.0

  • Return type added: string|int|null
  • Parameter name of parameter #1 changed: $arg to $array
  • Parameter type added for parameter #1 ($array): array
- array_key_first($arg)
+ array_key_first(array $array): string|int|null

PHP 7.3

  • Function added

array_key_first Function Availability

PHP VersionAvailability
PHP 8.5Upcoming Release Yes
PHP 8.4Supported (Latest) Yes
PHP 8.3Supported Yes
PHP 8.2Security-Fixes Only Yes
PHP 8.1Security-Fixes Only Yes
PHP 8.0Unsupported Yes
PHP 7.4Unsupported Yes
PHP 7.3Unsupported Yes
PHP 7.2Unsupported No
PHP 7.1Unsupported No
PHP 7.0Unsupported No
PHP 5.6Unsupported No
PHP 5.5Unsupported No
PHP 5.4Unsupported No
PHP 5.3Unsupported No