array_change_key_case Returns an array with all string keys lowercased or uppercased arrayarray_change_key_case arrayinput intcase array_change_key_case changes the keys in the input array to be all lowercase or uppercase. The change depends on the last optional case parameter. You can pass two constants there, CASE_UPPER and CASE_LOWER. The default is CASE_LOWER. The function will leave number indices as is. 1, "SecOnd" => 4); print_r(array_change_key_case($input_array, CASE_UPPER)); ?> ]]> &example.outputs; 1 [SECOND] => 4 ) ]]> 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.