int strncasecmp(const char *, const char *, size_t) __ATTR_PURE__
The strncasecmp() function is similar to strcasecmp(), except it only compares the first len characters of s1.
The strncasecmp() function returns an integer less than, equal to, or greater than zero if s1 (or the first len bytes thereof) is found, respectively, to be less than, to match, or be greater than s2. A consequence of the ordering used by strncasecmp() is that if s1 is an initial substring of s2, then s1 is considered to be "less than" s2.