computation performance skeleton

#include <stdio.h>

int main(int argc, char **argv) {
    int len = 10000000;
    char buf[8];
    for (int a = 1; a <= len; a++) {
        int c = a;
        int i = 0;
        while (c > 0) {
            buf[i] = '0' + (c % 10);
            c = c / 10;
            i++;
        }
        volatile int dont_optimize = i + buf[i];
    }
    return 0;
}