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Returns an array with all keys from input lowercased or uppercased. Numbered indices are left as is.
Returns an array with its keys lower or uppercased, or false if input is not an array.
Try out following example:
$input_array = array("FirSt" => 1, "SecOnd" => 4);
This will produce following result:
Array ( [FIRST] => 1 [SECOND] => 4 )