The bcmp() function compares byte string b1 against byte string b2, returning zero if they are identical, non-zero otherwise. Both strings are assumed to be len bytes long. Zero-length strings are always identical.
The bcmp() function conforms to IEEE Std 1003.1-2001 (“POSIX.1”). The IEEE Std 1003.1-2004 (“POSIX.1”) revision marked it as legacy and recommended the use of memcmp(3) instead. The IEEE Std 1003.1-2008 (“POSIX.1”) revision removed bcmp() from the specification.