Is the actual location where the elements inside the std::vector are stored in the heap or stack?

Question

As for vector<char> and vector<int>, the char elements and the int elements are both stored in the stack,but what about a vector<string>?

If I want to store a huge vector<string> with many strings, should I use new vector<string> to store my vector in the heap?

_"As for `vector` and `vector`, the `char` elements and the `int` elements are both stored in the stack"_: This is incorrect. `std::vector` always dynamically allocates its elements. — Miles Budnek, Jul 14 '23 at 01:53
Yes, that is correct. For any given type `T`, `sizeof(std::vector)` is constant. In fact that is the case for any type. For any type `T`, `sizeof(T)` is constant. — Miles Budnek, Jul 14 '23 at 02:06
@bolov Even `std::vector` allocates its elements externally. For all its oddities, `sizeof(std::vector)` is still constant. — Miles Budnek, Jul 14 '23 at 03:06
@MilesBudnek yes, of course. I was just making ... a joke. Because `sizeof(std::vector)` is the same across all `T`s, except `bool`. — bolov, Jul 14 '23 at 03:12
@keyzhao *"So the sizeof(vector) is always the same?"* -- See [why does sizeof vector and array gives different output](https://stackoverflow.com/q/58399544) and its duplicates. — JaMiT, Jul 14 '23 at 03:20

score 3 · Answer 1 · answered Jul 14 '23 at 01:48

You're over-thinking this.

Just use vector<string>. It manages the allocations for you, and sizeof(std::vector<...>) is fixed and reasonable.

Even then, if you were using std::array which acts a lot more like a C array, size and all, std::string will use dynamic allocation if necessary.

Using new std::vector<...> is hardly ever necessary.

1 Answers1