Array with fixed size at runtime

Question

I know I can use std::array<Type, Size> to a have an array of the type Type and a size, which is fix at compile time.

Furthermore, std::vector can be used, if the size is not fixed at compile time, but given at runtime.

Is there an std container, which can be set at runtime to a certain size and this size is than unchangeable? My intend is to get a compile error, if the size is changed after the creation of this container.

Of course this can be archived with old school arrays using pointers. Nevertheless, this also comes with the disadvantage of having to pass the pointer and the length to a function?

Not that I'm aware of. Closest would be a `std::unique_ptr`, I think + track of size. — Matthieu Brucher, Dec 11 '18 at 11:14
Indeed, a small class with a unique pointer + size would be easy enough to implement. — Matthieu Brucher, Dec 11 '18 at 11:16
you are looking for a properly sized `std::vector` where you use `operator[]` and forbid use of `push_back`. I dont think it is worth writing lots of extra code for that, just use what is already there — 463035818_is_not_an_ai, Dec 11 '18 at 11:17

score 4 · Accepted Answer · answered Dec 11 '18 at 11:24

Is there an std container, which can be set at runtime to a certain size and this size is than unchangeable?

No there's no such standard container providing that feature (yet).

You may write a simple wrapper class for std::vector using a fixed size like proposed in the answers here:

Constant-sized vector

Array with fixed size at runtime

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