array_keys

Function • Params and return types changed in PHP 8.0

Return all the keys or a subset of the keys of an array.

PHP 5
PHP 7
PHP 8.0
Improved
PHP 8.1
PHP 8.2-8.3
PHP 8.4
PHP 8.5
PHP 8.6

array_keys Function synopsis

array_keys(
    array $array,
    mixed $filter_value = <default>,
    bool $strict = false
  ): array

Parameters

$array

Typearray

An array containing keys to return.

$filter_value

OptionalTypemixedDefault value

If specified, then only keys containing this value are returned.

$strict

OptionalTypeboolDefault valuefalse

Determines if strict comparison (===) should be used during the search.

Return value

Typearray

Returns an array of all the keys in $array.

Changes to the array_keys Function

PHP 8.0

  • Return type added: array
  • Parameter name of parameter #1 changed: $arg to $array
  • Parameter type added for parameter #1 ($array): array
  • Parameter name of parameter #2 changed: $search_value to $filter_value
  • Parameter type added for parameter #2 ($filter_value): mixed
  • Parameter default value added for position #2 ($filter_value): <default>
  • Parameter type added for parameter #3 ($strict): bool
  • Parameter default value added for position #3 ($strict): false
  array_keys(
-     $arg,
+     array $array,
-     $search_value,
+     mixed $filter_value = <default>,
-     $strict
+     bool $strict = false
-   )
+   ): array

array_keys Function Availability

PHP VersionAvailability
PHP 8.6Upcoming Release Yes
PHP 8.5Supported (Latest) Yes
PHP 8.4Supported Yes
PHP 8.3Security-Fixes Only Yes
PHP 8.2Security-Fixes Only Yes
PHP 8.1Unsupported Yes
PHP 8.0Unsupported Yes
PHP 7.4Unsupported Yes
PHP 7.3Unsupported Yes
PHP 7.2Unsupported Yes
PHP 7.1Unsupported Yes
PHP 7.0Unsupported Yes
PHP 5.6Unsupported Yes
PHP 5.5Unsupported Yes
PHP 5.4Unsupported Yes
PHP 5.3Unsupported Yes