STL容器在堆栈和堆上 [英] STL containers on the stack and the heap

问题描述

如果std :: vector和friends是自我调整大小，这是否意味着如果我声明一个像这样的向量：

  std :: vector< string> myvec; 
  

然后它会使用更多堆栈调整大小，而：

  std :: vector< string> * myvec = new std :: vector< string>（）; 
  

会使用更多堆调整大小吗？

在堆栈中为基于堆栈的主体支付的唯一的东西是一个几个字节，内部缓冲区总是从堆中分配。

当你做一个vec = new vector（）可能不是很好。

If std::vector and friends are self resizing, does that mean if I declare a vector like so:

std::vector<string> myvec;

Then it'll resize using more stack, whereas:

std::vector<string> *myvec = new std::vector<string>();

Would resize using more heap?

解决方案

Vectors allocate on the heap in their internals.

The only thing you pay for in the stack for a stack based bector is a couple of bytes, the inner buffer will always be allocated from the heap.

So effectively when you do a vec = new vector() you are allocating a small quantity, which may not be really good.

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