如何缩小 std::vector 的大小? [英] How to downsize std::vector?

问题描述

当我不再需要以前保留的空间时，有没有办法调整 std::vector 的大小以降低容量?

Is there a way to resize a std::vector to lower capacity when I no longer need previously reserved space?

推荐答案

Effective STL，作者 Scott Meyers，第 17 条:使用 swap 技巧来减少多余的容量.

Effective STL, by Scott Meyers, Item 17: Use the swap trick to trim excess capacity.

vector<Person>(persons).swap(persons);

在那之后，persons 被缩小以适应".

After that, persons is "shrunk to fit".

这依赖于 vector 的复制构造函数只为被复制的元素分配所需的内存.

This relies on the fact that vector's copy constructor allocates only as much as memory as needed for the elements being copied.

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