c++ standard library <numeric> accumulate demo

#include <iostream>
#include <vector>
#include <numeric>

using namespace std;

int main()
{
int arr[] = {1, 2, 5, 10};
size_t array_size = sizeof(arr) / sizeof(arr[0]);
vector<int> ivec(arr, arr + array_size);
int sum = accumulate(ivec.begin(), ivec.end(), 0);
cout << sum << endl;

return 0;
}