- See that when we have an array, we usually index it with an array index of
0 <= i < len. - If
len = 0, then the only "acceptable"iis-1, since it's the greatest integer that is less thatlen=0.
-1 Is Sensible 0 <= i < len. len = 0, then the only "acceptable" i is -1, since it's the greatest integer that is less that len=0.