#include <stdio.h>
int sum_digits(int n) {
int sum = 0;
while (n > 0) {
int d = n % 10;
n /= 10;
sum += d;
}
return sum;
}
int main() {
int n = 12345;
printf("sum number: %d digits = %d\n", n, sum_digits(n));
return 0;
}
/*
run:
sum number: 12345 digits = 15
*/