/* sum_arr2.c -- sums the elements of an array */
#include <stdio.h>
#define SIZE 10
int sump(int * start, int * end);
int main(void)
{
    int marbles[SIZE] = {20,10,5,39,4,16,19,26,31,20};
    long answer;
    
    answer = sump(marbles, marbles + SIZE);
    printf("The total number of marbles is %ld.\n", answer);
    
    return 0;
}

/* use pointer arithmetic   */
int sump(int * start, int * end)
{
    int total = 0;
    
    while (start < end)
    {
        total += *start; // add value to total
        start++;         // advance pointer to next element
    }
    
    return total;
}