c/string/byte/memcmp

Compares the first bytes of the objects pointed to by  and. The comparison is done lexicographically.

The sign of the result is the sign of the difference between the values of the first pair of bytes (both interpreted as ) that differ in the objects being compared.

The behavior is undefined if access occurs beyond the end of either object pointed to by and. The behavior is undefined if either or  is a null pointer.

Return value
Negative value if  appears before  in lexicographical order.

Zero if and  compare equal, or if count is zero.

Positive value if appears after  in lexicographical order.