The correct answer is (as Rob said) the following:
iHoursTemp = iHoursTemp + (iZoneNew--) - iZoneOld;
The reason it is that way and not
iHoursTemp = iHoursTemp + iZoneNew - (--iZoneOld);
is a convention known as maximum munch strategy, which says that if there is more than one possibility for the next token, use (bite) the one that has the most characters. The possibilities in this case are - and --, -- is obviously longer.
