CODEWITHSUNDEEP
c++pointersvector
Ender
Ender

Reputation: 1778

Access first element of pointer to vector of object pointers?

I declare a shared_ptr to a vector of shared_ptr's to objects like so ...

std::shared_ptr<std::vector<std::shared_ptr<my_obj_t>>> vec =
    std::make_shared<std::vector<std::shared_ptr<my_obj_t>>>();

My problem is I need to access the first element in the array used internally by the vector. Before changing this to a shared_ptr of objects, it was just an object and I used data().

But now with the vector of shared_ptr's, I'm not sure how to access that first element so that I can add an offset to it and return a pointer of my_obj_t.

I'm trying to use something like 

(my_vec->data() + offset)

... where func requires a pointer to an array of my_obj_t's.

Thoughts?

Update: Before I was using it as ...

std::shared_ptr<std::vector<my_obj_t>> vec =
    std::make_shared<std::vector<my_obj_t>>();

And I would access it by

(vec->data() + offset)

Upvotes: 0

Views: 1000

Answers (3)

Ender
Ender

Reputation: 1778

Chris apparently didn't get around to making an answer, and since it was cleanest, this is what I used.

(*my_vec)[offset]->get()

Upvotes: 0

Caleth
Caleth

Reputation: 62531

To get a reference to the my_obj_t pointed to from offset

*my_vec->at(offset)

There isn't an array of my_obj_t anywhere

Upvotes: 1

L. F.
L. F.

Reputation: 20559

std::make_shared<std::vector<std::shared_ptr<my_obj_t>>>()

This constructs an empty vector of shared_ptrs.

My problem is I need to access the first element in the array used internally by the vector.

Since the vector is empty, the internal array you are imagining probably doesn't exist yet. So there is no way to access the first element of it. You have to add the elements before trying to use them.

Upvotes: 0

Related Questions