On Sat, 10 Apr 2004 03:43:46 +0100, Val Samko wrote
I did not find any functions in Date-Time library to add a number of months to a given day, or to obtain the last/first day of the month. I mean something like date add_month(const date&, int month_count); date first_date_of_month(const date&); date last_date_of_month(const date&);
Ok, sure. There are some examples that show how to do some of this.
I understand that I can use the month_iterator instead of add_month, and end_of_month_day instead of last_date_of_month, but since the functionality I described is heavily used in some applications (accounting for instance), it would be much simpler just to call add_month, ... functions.
Is there any particular reason why they are not provided?
No, not really -- lack of customer request, basically. add_month is a bit complicated in that it is unclear the desired behavior of adding into the 'ragged month end'. Basically the issue is: date d1(2004,Jan,28); date r1 = add_month(d1,1); //2004-Feb-28, fine date d2(2004,Jan,31); date r2 = add_month(d2,1); //presumably we want to back up to Feb 29? date r3 = add_month(d2,13); //presumably we want to back up to Feb 28? So given that this solution works for your domain, the library does have a solution which is unfortunately only documented in the iterator. Here is how I would write the 3 functions you are asking for: namespace boost { namespace gregorian { date first_date_of_month(const date& orig) { return date(orig.year(), orig.month(), 1); } date last_date_of_month(const date& orig) { int day = gregorian_calendar::end_of_month_day(orig.year(),orig.month()); return date(orig.year(), orig.month(), day); } date add_month(const date& d, int months) { typedef boost::date_time::month_functor<date> add_month_functor; add_month_functor mf(months); return (d + mf.get_offset(d)); } }} Of course the other option would be to include these in the date itself so you could write: date d(2004, Jan, 10); date fd = d.first_date_of_month(); date ld = d.last_date_of_month(); Do you prefer the oo style? For add month we could do: date next = ld.add_month(13); although the prefered syntax for add_month would actually be something like: date next = ld + months(13); There are some technical complications with the last syntax, but it should be doable given some time ;-) Thoughts? Jeff