Hello friends,

If you want to change the array keys in either upper case or lower case then you can use a predefined array function of PHP which is "array_change_key_case()". array_change_key_case returns an array with all keys from array lower or upper cased. Numbered indices are left as is.

Parameters: array: The array to work on case: Either CASE_UPPER or CASE_LOWER (default) Here is some example which will explain you clearly-

<?php
$inputArray = array("First" => 1, "Second" => 2);
print_r(array_change_key_case($inputArray, CASE_UPPER));
?>

Output:

Array
(
    [FIRST] => 1
    [SECOND] => 2
)

Here in another lower case example-

<?php
$inputArray = array("First" => 1, "Second" => 2);
print_r(array_change_key_case($inputArray, CASE_LOWER));
?>

Output:

Array
(
    [first] => 1
    [second] => 2
)