array_change_key_case() PHP Array Function

how to use array_change_key_case() function in an array in php language. php array function. Here is solution.I am explain array_change_key_case() use for php function.

array_change_key_case() :-

Definition & Usage :- The array_change_key_case() function returns array with all string keys converted into lowercase or uppercase. example:-

<?php 
$marks = array("math"=>"35", "hindi"=>"25");
print_r(array_change_key_case($age, CASE_UPPER));
?> 
output// 
array([MATH]=>35 [HINDI]=>25)