指向boost共享指针矢量的void指针

Question

i have a void pointer 我有一个空指针

void *vp;

I want to point it to vec_A inside a function where vec_A is passed as a reference, that is 我想将其指向vec_A内部的函数，其中vec_A作为参考传递，即

some_function(std::vector<boost::shared_ptr<A> >& vec_A)
{
   void *vp;
   //now i want vp to point to vec_A
}

and after I point vp to vec_A , how to I get it back as 在将vp指向vec_A ，如何将其恢复为

 std::vector<boost::shared_ptr<A> >

Answer 1

Address-of and cast: 地址和演员：

void * vp = &vec_A;   // address-of

std::vector< boost::shared_ptr<A> > & v =
     *static_cast< std::vector< boost::shared_ptr<A> >* >(vp);

Now v is a reference to the very same vector whose address you took in the line above. 现在v是对相同向量的引用，您在上一行中使用了其地址。