Php/docs/function.array-keys

• PHP Manual
• Array Functions
• Return all the keys or a subset of the keys of an array

array_keys

(PHP 4, PHP 5, PHP 7)

array_keys — Return all the keys or a subset of the keys of an array

Description

array_keys ( array $array ) : array

array_keys ( array $array , mixed $search_value [, bool $strict = FALSE ] ) : array

array_keys() returns the keys, numeric and string, from the array.

If a search_value is specified, then only the keys for that value are returned. Otherwise, all the keys from the array are returned.

Parameters

array

An array containing keys to return.

search_value

If specified, then only keys containing these values are returned.

strict

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

Return Values

Returns an array of all the keys in array.

Examples

Example #1 array_keys() example

<?php$array = array(0 => 100, "color" => "red");print_r(array_keys($array));$array = array("blue", "red", "green", "blue", "blue");print_r(array_keys($array, "blue"));$array = array("color" => array("blue", "red", "green"),               "size"  => array("small", "medium", "large"));print_r(array_keys($array));?>

The above example will output:

Array
(
    [0] => 0
    [1] => color
)
Array
(
    [0] => 0
    [1] => 3
    [2] => 4
)
Array
(
    [0] => color
    [1] => size
)

See Also

• array_values() - Return all the values of an array
• array_combine() - Creates an array by using one array for keys and another for its values
• array_key_exists() - Checks if the given key or index exists in the array
• array_search() - Searches the array for a given value and returns the first corresponding key if successful