Dating

QuiJohn

Check to see if the day defined by "year", "mon" and "day" is between dtStart and dtEnd:

        if (year >= dtStart.Year && year <= dtEnd.Year &&
           mon >= dtStart.Month && mon <= dtEnd.Month &&
           day >= dtStart.Day && day <= dtEnd.Day)
        {
           ok = true;
        }
        else
        {
           ok = false;
        }

:(

He said, "Boy I'm just old and lonely, But thank you for your concern, Here's wishing you a Happy New Year." I wished him one back in return.

Luc Pattyn

Ah, a false false generator in disguise. :)

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PIEBALDconsult

On a previous job, we had a small bug in a date validation routine... it was supposed to ensure that the date (year and month) was in the future. It checked the year, if it was greater than this year it returned true, if it was the same year it checked the month*. We encountered some data with a future year and a month of zero... :doh: * Further details omitted for brevity.

Bernhard Hiller

Hm. When setting dtStart to Dec 31, 2000 and dtEnd to Jan 1, 2100, there seems to be no date in this century which is ok. In case that there was nobody whom that guy wanted to date, that does not matter either.

Daniel Tak M

An example of how the World SHOULD work...

Jeremy Hutchinson

At first glance I thought it was just an awkward way to do it, as in why not just create a date from the MDY, then compare. Then I saw the real problem...

BillW33

I have far too much legacy code that does not check for data being in a valid range. :sigh:

Just because the code works, it doesn't mean that it is good code.

Luc Pattyn

in order to fix the bugs, you could write:

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

which still sits in the right forum. :)

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Camilo Sanchez

same happened to me, I just couldn't see what was wrong

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):

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.