It does actually.

"The strncmp() function is similar, except it compares only the first (at most) n bytes of s1 and s2."

Possibly it's years of string wrangling in C that sets me up here for being biased towards the compact way in which the C manpages state what the function will do, but 'early termination' because of zero length strings for comparisions returns 0 just as sure as comparing "" and "" would. And that 0 indicates a match...