int strcmp(const char *, const char *) __ATTR_PURE__
The strcmp() function compares the two strings
s1 and s2.
The strcmp() function returns an integer less than, equal to,
or greater than zero if s1 is found, respectively,
to be less than, to match, or be greater than s2. A
consequence of the ordering used by strcmp() is that if s1 is an initial
substring of s2, then
s1 is considered to be "less than"
s2.