如果你使用delphi6,用DaysBetween:
function DaysBetween(const ANow, AThen: TDateTime): Integer;
Description
Call DaysBetween to obtain the difference, in days, between two TDateTime values.
DaysBetween counts only whole days that have elapsed. Thus, DaysBetween reports the
difference between Dec 31, 1999 11:59 PM and Jan 1, 2000 11:58 PM as 0 because the
difference is one minute short of an entire day.