# PHP array_keys() Function

PHP Array Reference

## Example

Return an array containing the keys:

<?php
$a=array("Volvo"=>"XC90","BMW"=>"X5","Toyota"=>"Highlander");
print_r(array_keys($a));
?>
Run example »

## Definition and Usage

The array_keys() function returns an array containing the keys.

## Syntax

array_keys(array,value,strict)

Parameter | Description
--- | ---
array | Required. Specifies an array
value | Optional. You can specify a value, then only the keys with this value are returned

strict

Optional. Used with the value parameter. Possible values:

- true - Returns the keys with the specified value, depending on type: the number 5 is not the same as the string "5".
- false - Default value. Not depending on type, the number 5 is the same as the string "5".

## Technical Details

Return Value: | Returns an array containing the keys
PHP Version: | 4+
Changelog: | The strict parameter was added in PHP 5.0

## More Examples

## Example 1

Using the value parameter:

<?php
$a=array("Volvo"=>"XC90","BMW"=>"X5","Toyota"=>"Highlander");
print_r(array_keys($a,"Highlander"));
?>
Run example »

## Example 2

Using the strict parameter, false:

<?php
$a=array(10,20,30,"10");
print_r(array_keys($a,"10",false));
?>
Run example »

## Example 3

Using the strict parameter, true:

<?php
$a=array(10,20,30,"10");
print_r(array_keys($a,"10",true));
?>
Run example »

PHP Array Reference

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