MAC Address printing

Question

This is a code that gets some info about network the problem is when it prints the MAC address it prints it sometime normally and sometime with fff\'s like 00:21:84:a2:12:88

Answer 1

It looks like a signed/unsigned problem.

Try to cast into unsigned char :

  printf("> Successfully received Local MAC Address : %02x:%02x:%02x:%02x:%02x:%02x\n",
  (unsigned char) ifr.ifr_hwaddr.sa_data[0],
  (unsigned char) ifr.ifr_hwaddr.sa_data[1],
  (unsigned char) ifr.ifr_hwaddr.sa_data[2],
  (unsigned char) ifr.ifr_hwaddr.sa_data[3],
  (unsigned char) ifr.ifr_hwaddr.sa_data[4],
  (unsigned char) ifr.ifr_hwaddr.sa_data[5]);