由于它的作用就像一个哈希表，你会访问一个元素时有 O（1）时间由关键

Because it acts like a hash table, you will have O(1) time when accessing an element by a key.

如果您通过数组循环，自然你就会拥有 O（N）的时间。

If you are looping through the array, naturally you will have O(n) time.

如果你有时间，你其实可以看看PHP的实施阵列这里的

If you have time, you can actually check out PHP's implementation of array here