memcmp(3) BSD Library Functions Manual memcmp(3)
memcmp -- compare byte string
Standard C Library (libc, -lc)
#include <string.h> int memcmp(const void *s1, const void *s2, size_t n);
The memcmp() function compares byte string s1 against byte string s2. Both strings are assumed to be n bytes long.
The memcmp() function returns zero if the two strings are identical, oth- erwise returns the difference between the first two differing bytes (treated as unsigned char values, so that `\200' is greater than `\0', for example). Zero-length strings are always identical. This behavior is not required by C and portable code should only depend on the sign of the returned value.
The memcmp() function conforms to ISO/IEC 9899:1990 (``ISO C90''). BSD June 4, 1993 BSD
Mac OS X 10.12.3 - Generated Sun Feb 5 15:29:10 CST 2017