<?php // 一个基本的购物车，包括一些已经添加的商品和每种商品的数量。 // 其中有一个方法用来计算购物车中所有商品的总价格。该方法使用了一个closure作为回调函数。 class Cart {     const PRICE_BUTTER  = 1.00;     const PRICE_MILK    = 3.00;     const PRICE_EGGS    = 6.95;     protected   $products = array();     public function add($product, $quantity)     {         $this->products[$product] = $quantity;     }     public function getQuantity($product)     {         return isset($this->products[$product]) ? $this->products[$product] :                FALSE;     }     public function getTotal($tax)     {         $total = 0.00;         $callback =             function ($quantity, $product) use ($tax, &$total)             {                 $pricePerItem = constant(__CLASS__ . "::PRICE_" .                     strtoupper($product));                 $total += ($pricePerItem * $quantity) * ($tax + 1.0);             };         //使用用户自定义函数对数组中的每个元素做回调处理         array_walk($this->products, $callback);         return round($total, 2);;     } } $my_cart = new Cart; // 往购物车里添加条目 $my_cart->add('butter', 1); $my_cart->add('milk', 3); $my_cart->add('eggs', 6); // 打出出总价格，其中有 5% 的销售税. print $my_cart->getTotal(0.05) . "\n"; // The result is 54.29 ?>

function html($code , $id="", $class=""){ if ($id !== "") $id = " id = \"$id\"" ; $class = ($class !== "")? " class =\"$class\">":">"; $open = "<$code$id$class"; $close = "</$code>"; return function ($inner = "") use ($open, $close){ return "$open$inner$close";     }; }

<?php $fib = function($n) use(&$fib) {     if($n == 0 || $n == 1) return 1;     return $fib($n - 1) + $fib($n - 2); }; echo $fib(2) . "\n"; // 2 $lie = $fib; $fib = function(){die('error');};//rewrite $fib variable echo $lie(5); // error   because $fib is referenced by closure

<?php $recursive = function () use (&$recursive){ // The function is now available as $recursive }

<?php $result = 0; $one = function() {     var_dump($result); }; $two = function() use ($result) {     var_dump($result); }; $three = function() use (&$result) {     var_dump($result); }; $result++; $one();    // outputs NULL: $result is not in scope $two();    // outputs int(0): $result was copied $three();    // outputs int(1)