#include <numeric>
#include <functional>
#include <iostream>

int main()
{
  double arr[] = { 1, 2, 3, 4, 5 };
  std::cout << "Summe   = " 
            << std::accumulate(arr, arr+5, 0.0) << '\n';
  std::cout << "Produkt = " 
            << std::accumulate(arr, arr+5, 1.0, std::multiplies<double>()) << '\n';
}