PHP - How to change array keys from uppercase to lowercase?

The array_change_key_case() function changes all keys in an array to lowercase or uppercase.

Syntax:

array_change_key_case(array,case); array - The array to work on CASE_LOWER - Default value. Changes the keys to lowercase CASE_UPPER - Changes the keys to uppercase

This function takes array as a first parameter, It will return FALSE if given input is not an array.
Second parameter is optional,you can pass either CASE_LOWER or CASE_UPPERand default value is “CASE_LOWER”. This function is supported from PHP 4.2 and above.

Example :

<?php $input_array = array("FirSt" => 1, "SecOnd" => 4); print_r(array_change_key_case($input_array, CASE_UPPER)); ?> // output : Array (     [FIRST] => 1     [SECOND] => 4 )

Example :

<?php $input_array = array("FirSt" => 1, "SecOnd" => 4); print_r(array_change_key_case($input_array)); ?> // output : Array (     [first] => 1     [second] => 4 )