int strcmp_P(const char *, const char *) __ATTR_PURE__
The strcmp_P() function is similar to strcmp() except that s2 is pointer to a string in program space.
The strcmp_P() 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_P() is that if s1 is an initial substring of s2, then s1 is considered to be "less than" s2.