// Ex6_09. cpp Using the decltype operator
#include <iostream>
#include <typeinfo>
using std::cout;
using std::endl;

template<class T1, class T2>
auto product(T1 v1[], T2 v2[], size_t count)->decltype(v1[0]*v2[0])
{
  decltype(v1[0]*v2[0]) sum(0);
  for(size_t i = 0; i<count ; i++) sum += v1[i]*v2[i];
  return sum;
}

int main()
{
  double x[] = {100.5, 99.5, 88.7, 77.8};
  short y[] = {3, 4, 5, 6};
  long z[] = {11L, 12L, 13L, 14L};
  size_t n = 4;
  cout << "Result type is "<< typeid(product(x, y, n)).name() << endl;
  cout << "Result is " << product(x, y, n) << endl;
  cout << "Result type is "<< typeid(product(z, y, n)).name() << endl;
  cout << "Result is " << product(z, y, n) << endl;
  return 0;
}