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array_keys

(PHP 4, PHP 5)

array_keysReturn all the keys or a subset of the keys of an array

Description

array array_keys ( array $array [, mixed $search_value = NULL [, bool $strict = false ]] )

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

If the optional 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.

Changelog

Version Description
5.0.0 Added the strict parameter.

Examples

Example #1 array_keys() example

<?php
$array 
= array(=> 100"color" => "red");
print_r(array_keys($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

PHP Manual