如何实现C ++ std :: vector？ [英] How is C++ std::vector implemented?

问题描述

我一直使用 std :: vector 很多，最近我问自己这个问题： std :: vector 已实现？

我有两个选择：

使API感觉像随机访问（即重载 operator [] ）。

2）使用 new ，例如 Foo * temp = new Foo [20] ：我相信他们做这样的事情，但后来又提出了一个问题。他们总是分配一个最大（ uint32_t ）存储以提供随机访问吗？

或者还有其他我应该注意的事情？

这是不可能实现 en.cppreference.com/w/cpp/container/vector> std :: vector< T> ，因为标准保证元素该列表将被保存在连续的内存中。

I have been using std::vector a lot, and recently I asked myself this question: "How is std::vector implemented?"

I had two alternatives:

1) Linked list, and then making the API feel like random access (i.e. overloading operator[]).

2) Using new, e.g. Foo* temp = new Foo[20]: I believe they do something like this, but then it raises one more question. Do they always allocate a maximum (uint32_t) storage to give random access? (This is inefficient in terms of memory.)

Or is there something else that I should be aware of?

解决方案

It's implemented by using an underlying array.

It's not possible to implement a std::vector<T> with a linked list because the standard guarantees the elements in the list will be held in contiguous memory.

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