/* ----------------------------------------------------------------------- **
   Self Test Exercise 21.4:  Computing the product of an array iteratively.
** ----------------------------------------------------------------------- */

#include <stdio.h>                                   
#define N 5
int sum( int ar[], int n );

void main( void )                                                      
{
    int primes[] = { 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41 };          
    int answer;   

    printf( "\nCalculating sum of first %i primes\n", N );  
    answer = sum( primes, N );
    printf( "Sum = %i\n\n", answer );  
}
   
/* ---------------------------------------------------------------- */
int 
sum( int a[], int n ) {
    if (n == 1)  return a[0];
    else return a[0] + sum( &a[1], n-1 ); 
}