sum of integer in array c++

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