Lab 12 Solutions.

sol.c

int recursive_sum(int num) {
  int ones = num % 10;
  if (num == 0 ) {
    return 0;
  }
  return ones + recursive_sum(num / 10);
}

void reverse_string(char *start, char *end) {
  char temp;
  if (start >= end) {
  return;
  }
  temp = *start;
  *start = *end;
  *end = temp;
  reverse_string(start + 1, end - 1);
}