C job interview - casting and comparing

Question

I was confronted with a tricky (IMO) question. I needed to compare two MAC addresses, in the most efficient manner.

The only thought that crossed my mind in that moment

Answer 1

May be he had in mind a definition of MAC that used unsigned char and was thinking to:

int isEqual(MAC* addr1, MAC* addr2) { return strncmp((*addr1).data,(*addr2).data,6)==0; }

which implies a cast from (unsigned char *) to (char *). Anyway bad question.