PHP 函数中如何在返回值中传递多个值？

function calculate($a, $b) {  return array($a + $b, $a - $b);}list($sum, $diff) = calculate(10, 5);echo $sum; // 输出：15echo $diff; // 输出：5

class Result {  public $sum;  public $diff;}function calculate($a, $b) {  $result = new Result();  $result->sum = $a + $b;  $result->diff = $a - $b;  return $result;}$result = calculate(10, 5);echo $result->sum; // 输出：15echo $result->diff; // 输出：5

function swap(&$a, &$b) {  $temp = $a;  $a = $b;  $b = $temp;}$a = 10;$b = 5;swap($a, $b);echo $a; // 输出：5echo $b; // 输出：10

function getCartStats() {  $items = array(    array('name' => 'Apple', 'price' => 10, 'quantity' => 2),    array('name' => 'Orange', 'price' => 5, 'quantity' => 3)  );  $total_price = 0;  $total_quantity = 0;  foreach ($items as $item) {    $total_price += $item['price'] * $item['quantity'];    $total_quantity += $item['quantity'];  }  return array($total_price, $total_quantity);}list($total_price, $total_quantity) = getCartStats();echo '总价格：' . $total_price; // 输出：35echo '总数量：' . $total_quantity; // 输出：5

class CartStats {  public $total_price;  public $total_quantity;}function getCartStats() {  $items = array(    array('name' => 'Apple', 'price' => 10, 'quantity' => 2),    array('name' => 'Orange', 'price' => 5, 'quantity' => 3)  );  $stats = new CartStats();  $stats->total_price = 0;  $stats->total_quantity = 0;  foreach ($items as $item) {    $stats->total_price += $item['price'] * $item['quantity'];    $stats->total_quantity += $item['quantity'];  }  return $stats;}$stats = getCartStats();echo '总价格：' . $stats->total_price; // 输出：35echo '总数量：' . $stats->total_quantity; // 输出：5