C version of recursive sum (with sentinel)

sum.c

#include <stdio.h>

int sum(int *numbers) {
	if (numbers[0] == -1) {
		return 0;
	} else {
		return numbers[0] + sum(numbers + 1);
	}
}

int main() {
	int numbers[] = {1, 2, 3, 4, 5, 6, -1};
	printf("Result: %d\n", sum(numbers));
	return 0;
}