PHP函数面试必备知识点，解密数组处理函数的用法

$numbers = [1, 2, 3, 4, 5];$squaredNumbers = array_map(fn ($n) => $n ** 2, $numbers);

$words = ['apple', 'banana', 'cherry', 'dog', 'cat'];$filteredWords = array_filter($words, fn ($word) => strlen($word) > 3);

$numbers = [1, 2, 3, 4, 5];$sum = array_reduce($numbers, fn ($acc, $n) => $acc + $n);

$cart = [    ['product' => 'Apple', 'quantity' => 2],    ['product' => 'Orange', 'quantity' => 1],    ['product' => 'Banana', 'quantity' => 3],];// 计算总数量$totalQuantity = array_reduce($cart, fn ($acc, $item) => $acc + $item['quantity']);// 过滤商品数量大于 2 的项$filteredCart = array_filter($cart, fn ($item) => $item['quantity'] > 2);// 以商品名称为键映射商品信息$indexedCart = array_map(fn ($item) => [$item['product'] => $item], $cart);