How can I create a shared_ptr to a std::vector?

Question

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

std::vector mVector;
shared_ptr> mSha         


        

Answer 1

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

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Three alternatives:

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

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

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

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

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

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

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