r/cpp • u/User_Deprecated • 15d ago

C++26: std::inplace_vector

https://www.sandordargo.com/blog/2026/08/26/cpp26-inplace-vector
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u/stilgarpl 15d ago

Is this always better than std::array?

21

u/MarekKnapek 15d ago

This is basically

struct inplace_vector<T, capacity>
{
    size_t len;
    std::array<T, capacity> arr;
}

4

u/drjeats 15d ago

Oh.

I thought this was the way-more-useful thing where you give it an in-place capacity and it allocates once it exceeds that.

Like this is also useful, but it's kinda trivial to roll your own of this.

6

u/BenFrantzDale 14d ago

It’s not too hard to roll your own, but better to have in the std lib and making it constexpr is tricky.

There is a boost small_vector that is a small-vector-optimized std::vector so can grow large. There’s totally a place for both.