c++ - unique_ptr<int[]> or vector<int>?

Question

If you don't need dynamic growth and don't know the size of the buffer at compile time, when should unique_ptr<int[]> be used instead of vector<int> if at all?

Is there a significant performance loss in using vector instead of unique_ptr?

Answer 1

There is no performance loss in using std::vector vs. std::unique_ptr<int[]>. The alternatives are not exactly equivalent though, since the vector could be grown and the pointer cannot (this can be and advantage or a disadvantage, did the vector grow by mistake?)

There are other differences, like the fact that the values will be initialized in the std::vector, but they won't be if you new the array (unless you use value-initialization...).

At the end of the day, I personally would opt for std::vector<>, but I still code in C++03 without std::unique_ptr.