c++ static array wrapper

Question

I'm trying to build a wrapper class for static array, which should behave like a standard static array.

int main()
{
  int t[2][3] = {{77, 2, 3}, {4, 5, 6}};
  auto a = make_array(t);
  auto b = a[0]; // gives a ArrayWrapper<int, 3>
  auto c = b[0]; // gives an int of value 77;
  return 0;
}

So far I've written the following class and construction function:

#include <cstdlib>

template <typename T, size_t N>
struct ArrayWrapper;

template<typename T, size_t N>
auto make_array(T const (&tab) [N])
{
  return ArrayWrapper<T, N>(tab);
}


template <typename T, size_t N>
struct ArrayWrapper
{
  ArrayWrapper(T const (&tab)[N])
    : t(tab)
  {
  }

  template<typename U, size_t M>
    ArrayWrapper<U, M> operator[] (size_t i)
    {
      return make_array<U, M>(t[i]);
    }

  T const & t;
};

Unfortunately, during the affectation of b g++ gives me the following error:

error: no match for ‘operator[]’ (operand types are ‘ArrayPrinter<int [3], 2>’ and ‘int’)
   auto b = a[0];

Plus I don't know how to specialize the [] operator to return a basic type when ArrayWrapper just contains has one dimension. I'm guessing I should specialize the operator when T is not an array but I could not make it compile.

Can anyone tell me how to help g++ make the template deduction for the [] operator when T is an array?

Can anyone tell me how to tell the [] operator to return the basic type when T is not an array anymore?

You mean I could inherit from std::array to override the [] operator to do as I want ? — Dorian, May 22 '18 at 14:57
no, simply use `std::array`. The `std::array>::operator[]` does already what you want if i understood correctly (ie it returns an array on which you can call `operator[]` again to get the element) — 463035818_is_not_an_ai, May 22 '18 at 15:21

c++ static array wrapper

0 Answers0