#include <iostream>
#include <numeric>
#include <algorithm>
#include <iterator>

int main() {
  const size_t size      = 5;
        double arr[size] = { 5.0, 4.0, 3.0, 2.0, 1.0 };

  std::cout << "Array: ";
  std::copy(arr, arr + size, std::ostream_iterator<double>(std::cout, " "));
  std::cout << std::endl;

  std::cout << "Sum: " << std::accumulate(arr, arr + size, 0.0) << std::endl;

  std::cout << "Reverse array: ";
  std::reverse_copy(arr, arr + size, std::ostream_iterator<double>(std::cout, " "));
  std:cout << std::endl;

  return 0;
}

Array: 5 4 3 2 1 
Sum: 15
Reverse array: 1 2 3 4 5