将std :: stack复制到std :: vector中 [英] Copy std::stack into an std::vector

问题描述

以下代码是否被标准保证可以正常工作(假设st不为空)?

Is the following code guaranteed by the standard to work(assuming st is not empty)?

#include <vector>
#include <stack>
int main()
{
   extern std::stack<int, std::vector<int> > st;
   int* end   = &st.top() + 1;
   int* begin = end - st.size();
   std::vector<int> stack_contents(begin, end);
}

推荐答案

是.

std :: stack 只是一个容器适配器.

std::stack is just a container adapter.

您可以看到 .top()实际上是(§23.3.5.3.1)

You can see that .top() is actually (§23.3.5.3.1)

reference top() { return c.back(); }

其中 c 是容器，在这种情况下为 std :: vector

Where c is the container, which in this case is a std::vector

这意味着您的代码基本上被翻译为:

Which means that your code is basically translated into:

   extern std::vector<int> st;
   int* end   = &st.back() + 1;
   int* begin = end - st.size();
   std::vector<int> stack_contents(begin, end);

并且由于确保 std :: vector 是连续的，因此应该没有问题.

And as std::vector is guaranteed to be continuous there should be no problem.

但是，这并不意味着这是一个好主意.如果您需要使用这种"hacks"，则通常表明设计不良.您可能想从一开始就使用 std :: vector .

However, that does not mean that this is a good idea. If you need to use "hacks" like this it is generally an indicator of bad design. You probably want to use std::vector from the beginning.

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