Both strcoll() and strxfrm(3C) provide for locale-specific string
sorting. strcoll() is intended for applications in which the number of comparisons per string is small. When strings are to be compared a number of times, strxfrm(3C) is a more appropriate function because the transformation process occurs only once.
Upon successful completion, strcoll() returns an integer greater than, equal to, or less than zero in direct correlation to whether string s1 is greater than,
equal to, or less than the string s2. The comparison is based on strings interpreted as appropriate to the program's locale for category LC_COLLATE (see setlocale(3C)).
On error, strcoll() may set errno, but no return value is reserved to indicate an error.