#include <iostream>
#include <sstream>

using std::cout;
using std::endl;
using std::stringstream;

// Here's how you would use the compiler+templates to calculate a
// compile-time constant.  Note: nobody does this in real life.
template <int n>
struct fibonacci {
  static constexpr int value = fibonacci<n-1>::value + fibonacci<n-2>::value;
};

template <>
struct fibonacci<0>
{
  static constexpr int value = 0;
};
template <>
struct fibonacci<1>
{
  static constexpr int value = 1;
};


int main(int argc, char **argv)
{
  cout << "The compile-time constant fib(40) is: "
       << fibonacci<40>::value << endl;

  // Since fibonacci<> generates compile-time constants, you can create
  // arrays, etc, using it.
  stringstream s;
  int array[fibonacci<4>::value];
  for (int i = 0; i < fibonacci<4>::value; ++i) {
    array[i] = i;
    if (i != 0) {
      s << ", ";
    }
    s << array[i];
  }
  cout << "Initialized a " << fibonacci<4>::value << "-element array to: {"
       << s.str() << "}" << endl;

  return 0;
}