Summing an Array with random values - c

Question

I need to make a function that sums my array, which is filled with random values. My function only returns 0 and not an actual summation of the array. I don't have much experience with arrays or random values, how can I code my arrSum function to give me the sum of the array when called?
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define SIZE 1000
int arrSum(int arr[SIZE], int b) {
if (b < 0) {
return 0;
} else {
return arr[b] + arrSum(arr, b - 1);
}
}
int main() {
int inputNum;
int i;
int arr1[SIZE];
int sum;
srand(time(0));
printf("Enter an integer between 0 and 1000: ");
scanf("%d", &inputNum);
sum = arrSum(arr1, inputNum);
printf("sum: %6d\n\n", sum );
printf(" Pos | Val\n");
printf("-------------\n");
for (i = 0; i < inputNum; i++) {
printf("%4d |%4d\n", i, rand() % 1001);
}
return 0;
}

Answer 1

The reason is initially there are no values in the array. But only 0.
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define SIZE 1000
int arrSum(int arr[SIZE], int b){
if (b < 0) return 0;
else return arr[b] + arrSum(arr, b-1);
}
int main(){
int inputNum;
int i,q;
int arr1[SIZE] = {0};
int sum;
srand(time(0));
printf("Enter an integer between 0 and 1000: ");
scanf("%d",&inputNum);
for(q=0;q<inputNum;q++){
arr1[q] = rand() % 1001;
}
sum = arrSum(arr1, inputNum);
printf("sum: %6d\n\n", sum );
printf(" Pos | Val\n");
printf("-------------\n");
for (i = 0; i < inputNum; i++){
printf("%4d |%4d\n", i,arr1[i]);
}
return 0;
}

Answer 2

The logic behind finding the sum inside the function is correct, assuming that b is within the range of the array indices. The real problem is that your array is not filled with random numbers - it is filled with zeros.
When you do
int arr1[SIZE] = {0};
you are initializing each element to 0, and are not changing it at any point during the program. So, your function returns the sum from indices 0 to b, but this turns out to be 0.