Is it possible to have a std::array member whose size is unkown but evaluated at compile time? [closed]

Question

std::get's index is not known, but evaluated at compile time. I want to do something very similar to std::get's functionality with an std::array member.

Take this struct:

template<size_t size>
struct ArrayWrapper {
   std::array<int, size> arr;
};

I would want to be able to do something like this: ArrayWrapper<4> foo; Here, arr inside foo would be initialized at compile time with a size of 4. The code above doesn't work, which doesn't make sense to me since size is known at compile time.

Is there any way of making this work?

Answer 1

Note the corrected order of template arguments

template<size_t size>
struct ArrayWrapper {
   std::array<int, size> arr;
};

Answer 2

The template argument for std::array are reversed in your code. It should instead be:

template<size_t size>
struct ArrayWrapper {
//------------vvv--vvvv----------->note the order is changed here
   std::array<int, size> arr;
};

int main()
{
    ArrayWrapper<4> obj; //works
}