# array_change_key_case

(PHP 4 >= 4.2.0, PHP 5, PHP 7)

array_change_key_case — Changes the case of all keys in an array

### Description

array_change_key_case ( array `$array` [, int `$case` = CASE_LOWER ] ) : array

Returns an array with all keys from `array` lowercased or uppercased. Numbered indices are left as is.

### Parameters

`array`

  The array to work on

`case`

  Either `CASE_UPPER` or `CASE_LOWER` (default)

### Return Values

Returns an array with its keys lower or uppercased, or `FALSE` if `array` is not an array.

### Errors/Exceptions

Throws `E_WARNING` if `array` is not an array.

### Examples

Example #1 array_change_key_case() example

`<?php
$input_array = array("FirSt" => 1, "SecOnd" => 4);
print_r(array_change_key_case($input_array, CASE_UPPER));
?>`

The above example will output:

    Array
    (
        [FIRST] => 1
        [SECOND] => 4
    )

### Notes

> Note:

> If an array has indices that will be the same once run through this function (e.g. "`keY`" and "`kEY`"), the value that is later in the array will override other indices.