strcmp - compare strings
Standard C Library (libc, -lc)
strcmp(const char *str1, const char *str2);
The two strings str1 and str2 are compared lexicographically.
If str1 sorts before str2, -1 is returned.
If str1 sorts after str2, 1 is returned.
If str1 is the same as str2, 0 is returned.
The sort order used is derived from the natural ordering of the numerical values of (unsigned) characters.