idimka39

$func = 'trim';
if (function_exists($func)) echo call_user_func($func,' Test ');

$_POST['function'] = 'trim';
$array = [' a', 'b '];
$allowedFunctions = ['trim'];

if (function_exists($_POST['function']) && in_array($_POST['function'], $allowedFunctions)) {
    $results = array_map($_POST['function'], $array);
    print_r($results);
}