. */ /** * Since PHP has a built-in concatenation operator, there is no function to do concatenation. * But for filters and transforms, we want to express a function for concatenation. */ function concat() { // concat(...) // splat operator in PHP 5.3 $string = ''; foreach (func_get_args() as $arg) { $string .= $arg; } return $string; } /** * Sum all input parameters * @return float|int */ function sum() { // concat(...) // splat operator in PHP 5.3 $sum = 0.0; foreach (func_get_args() as $arg) { $sum += floatval($arg); } return $sum; } /** * Sum all input parameters * @return float|int */ function multiply() { // concat(...) // splat operator in PHP 5.3 $product = ''; $first = true; foreach (func_get_args() as $arg) { if (is_numeric($arg)) { if ($first) { $product = floatval($arg); $first = false; } else { $product *= floatval($arg); } } } return $product; }