strcoll() - compare strings according to current collation
#include <string.h>
int strcoll (const char *s1, const char *s2)
The strcoll(3) function lexicographically compares the null-terminated strings s1 and s2 according to the current locale collation and returns an integer greater than, equal to, or less than 0, according as s1 is greater than, equal to, or less than s2.
memcmp(3)
setlocale(3)
strcmp(3)
strxfrm(3)