PHP 关联数组 是基于哈希实现的,所以查找和新增都是 O(1) 嘛? - V2EX
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Nicolay
V2EX    PHP

PHP 关联数组 是基于哈希实现的,所以查找和新增都是 O(1) 嘛?

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  •   Nicolay 2020-01-04 19:40:40 +08:00 4026 次点击
    这是一个创建于 2117 天前的主题,其中的信息可能已经有所发展或是发生改变。
    4 条回复    2020-01-05 12:49:07 +08:00
    Austaras
        1
    Austaras  
       2020-01-04 20:08:32 +08:00
    天底下哪有这样的好事
    kkk330
        2
    kkk330  
       2020-01-04 20:25:32 +08:00 via iPhone
    大多数情况下是这样的,但是没记错的话,php5 数组解决 hash 冲突的方式是往 bucket 下挂 bucket,搞了个链表,所以当 hash 冲突的时候这里不是 O ( 1 ),php7 没看不清楚,反正 hash 冲突解决方法就那几种;再一个就是 hash 表容量到阈值,一般扩容一倍,并且复制&重新 hash 原来的,这里的开销也不小
    xiaotianhu
        3
    xiaotianhu  
       2020-01-05 12:48:54 +08:00   2
    xiaotianhu
        4
    xiaotianhu  
       2020-01-05 12:49:07 +08:00
    哈希表碰撞攻击了解一下
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