Dating

[Marc Clifton]

Sadly, I've written code like that. :doh: Marc

[Stefan_Lang]

Minor correction. Try:

ok=!(year<dtStart.Year||(year==dtStart.Year&&(month<dtStart.Month||(year==dtStart.Year&&month==dtStart.Month&&day<dtStart.Day)))||
year>dtEnd.Year||(year==dtEnd.Year&&(month>dtEnd.Month||(year==dtStart.Year&&month==dtEnd.Month&&day>dtEnd.Day))))

Else you'll end up with 'valid' dates that are well within the month/date bracket, but in the wrong year(s)! hth :suss:

[Luc Pattyn]

I disagree. :)

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[johannesnestler]

Remembers me to some date comparisons I have done with plain C - long ago :-O (but mine were at least correct :-)) I was very happy when I had to do it the first time with C# and found out I can do it like this:

        DateTime dtPast = new DateTime(2009, 9, 9);
        DateTime dtNow = new DateTime(2010, 10, 10);
        DateTime dtFuture = new DateTime(2011, 11, 11);
        bool bIsBetween = dtNow > dtPast && dtNow < dtFuture;

[Jorgen Sigvardsson]

Yes, but you only do it once, and then when you realize your blunder, you promise yourself to never go there again. Right? :D

-- Kein Mitleid Für Die Mehrheit

[Marc Clifton]

Jörgen Sigvardsson wrote:

, you promise yourself to never go there again. Right?

Exactly. And generalizing the blunder, you realize how evil "if" statements actually are and carefully consider the use of them! Marc

[Jorgen Sigvardsson]

I stopped using branches years ago. It's my way or the highway! :D

-- Kein Mitleid Für Die Mehrheit

[jsc42]

Or (in no particular language):

long ymd = (year * 12 + month) * 31 + day
bool ok = ymd >= (dtStart.Year * 12 + dtStart.Month) * 31 + dtStart.Day
&& ymd <= (dtEnd.Year * 12 + dtEnd.Month) * 31 + dtEnd.Day

This is still in the right forum as it permits 31st Nov and 33rd Feb and 0th May, -9th day of the 17th month etc. without fixing them properly; but valid dates work. An even more horrible way with similar failings, but much faster would be (using << as a shift left logical operator and | as a bitwise OR):

long ymd = year << 9 | month << 5 | day
bool ok = ymd >= (dtStart.Year << 9 | dtStart.Month << 5 | dtStart.Day)
&& ymd <= (dtEnd.Year << 9 | dtEnd.Month << 5 | dtEnd.Day)

This assumes less than 32 days per month (2^5) and less than 16 months per year (2^4). The year << 9 bits are year * 32 * 16. So 33rd Feb and -9th day of the 17th month would be somewhat disasterous.

[Luc Pattyn]

the shifting way is what I would actually do when DateTime were not available; with a little optimization:

int ymd = (((year<<4)+month)<<5)+day;
eyc.

IMO it is the cheapest mapping from dates to integers that supports chronological ordering. I do add parentheses, for readability if nothing else. :)

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[Prerak Patel]

DateTime dt = new DateTime(year, month, day);
return (dt <= dtEnd & dt >= dtStart);

How about this one? Enclosing it in try catch will cop with invalid dates too.