#include <stdio.h>
#include <stdlib.h>

unsigned long turnOnIth(unsigned long value, int i) {
    return value | (1L << i);
}

int main(int argc, const char *argv[]) {
    if (argc == 1) {
        return 0;
    }
    
    unsigned long x = atoi(argv[1]);

    // flip least significant bit
    x ^= 1;

    // turn on index-7th bit
    x = turnOnIth(x, 7);


    /* Test if index-7th bit is on */
    if (x & 0x80) {
        printf("index-7th bit is on!\n");
    }
    
    return 0;
}