The signature of a generic comparison function.
A comparison function represents an ordering on a type of objects. A total ordering on a type means that for two values, either they are equal or one is greater than the other (and the latter must then be smaller than the former).
Comparator function represents such a total ordering by returning
- a negative integer if
ais smaller than
- zero if
ais equal to
- a positive integer if
ais greater than