accumulate(a.begin(), a.end(), 0)
// C++ program to demonstrate working of accumulate()
#include <iostream>
#include <numeric>
using namespace std;
// User defined function that returns sum of
// arr[] using accumulate() library function.
int arraySum(int a[], int n)
{
int initial_sum = 0;
return accumulate(a, a+n, initial_sum);
}
int main()
{
int a[] = {5 , 10 , 15} ;
int n = sizeof(a)/sizeof(a[0]);
cout << arraySum(a, n);
return 0;
}