数组 字符串之间的 处理

$goods_id = (int)$goods_id;
        // 先从COOKIE中取出这前浏览过的商品
        $goods = cookie('beforeViewGoods'); // 1,2,3,4,5
        $goods = explode(',', $goods);
        // 把当前浏览的商品放到数组中的第一个位置上
        array_unshift($goods, $goods_id);
        // 去重
        $goods = array_unique($goods);
        if(count($goods) > 5)
        {
            $goods = array_splice($goods, 0, 5);
        }
        $goods = implode(',', $goods);
        $goods = trim($goods, ',');