如何为std :: vector创建shared_ptr？ [英] How can I create a shared_ptr to a std::vector?

问题描述

我需要为std :: vector创建一个shared_ptr，正确的语法是什么？

I need to create a shared_ptr to a std::vector, what is the correct syntax?

std::vector<uint8_t> mVector;
shared_ptr<std::vector<uint8_t>> mSharedPtr = &mVector;

上面的代码无法编译。

谢谢。

推荐答案

您要尝试的是让智能指针管理堆栈对象。这是行不通的，因为堆栈对象在超出范围时会自行杀死。智能指针不能阻止它执行此操作。

What you are trying to do is to let a smart pointer manage a stack object. This doesn't work, as the stack object is going to kill itself when it goes out of scope. The smart pointer can't prevent it from doing this.

std::shared_ptr<std::vector<uint8_t> > sp;
{
   std::vector<uint8_t> mVector;
   sp=std::shared_ptr<std::vector<uint8_t> >(&mVector);
}
sp->empty();   // dangling reference, as mVector is already destroyed

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三种选择：

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Three alternatives:

（1）初始化向量，并通过以下方式对其进行管理 shared_ptr ：

(1) Initialize the vector and let it manage by the shared_ptr:

auto mSharedPtr = std::make_shared<std::vector<uint8_t> >(/* vector constructor arguments*/);

（2）管理向量的副本（通过调用向量副本构造函数）：

(2) Manage a copy of the vector (by invoking the vector copy constructor):

std::vector<uint8_t> mVector;
auto mSharedPtr = std::make_shared<std::vector<uint8_t> >(mVector);

（3）移动向量（通过调用向量移动构造函数）：

(3) Move the vector (by invoking the vector move constructor):

std::vector<uint8_t> mVector;
auto mSharedPtr = std::make_shared<std::vector<uint8_t> >(std::move(mVector));
//don't use mVector anymore.

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