Date Calculation Does Not Factor In Leap Year about calculator HOT 6 CLOSED

I believe that test case is incorrect. Per https://www.timeanddate.com/date/dateadded.html?m1=02&d1=20&y1=2019&type=add&ay=2&am=&aw=&ad=6&rec= the correct value was returned. When you add years, you do not convert them to days, you just add years. Does it reproduce when starting with Feb-1 and adding 31 days or Feb-28 00:00 and adding 25 hours?

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This is your friendly Microsoft Issue Bot. I created this issue automatically as requested by a team member.

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I agree with @benjaminkwilliams. I think it should be asked what does the user expect when a year is added to a date, if the next day in the next year or the 365th next day. I find it more likely to be the first one. Otherwise, the answer for adding y years to a date month/day/year would be month/day - leap years in that period of time/year+y, and saying that 20 years after 02/20/2019 is 02/15/2039 sounds odd to me.
However, if we stick to the definition of adding a year that Benjamin and I propose, it would be still needed to define what date is a year after any February 29th.

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I agree with @benjaminkwilliams and @marcomontoya, a year is not defined as 365 days neither as "Earth doing a full loop around the sun (~365.24219 days)", but as the same the same day number and month but Year+1.

We should also keep in mind that the Calculator application manages more than the Gregorian calendar.

Think about birthdays or anniversaries, you don't celebrate your birthday 1 day before before the current year was a leap one.

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I concur, the calculator is behaving correctly. It is indeed taking leap years into account, by not treating a year as 365 days. This is akin to not every month being 30 days.

In both cases, the calculator is doing the correct thing.

• Consider March 31st (of any year) plus one month. The result cannot be April 31st, because April only has 30 days. So the result becomes April 30th.
  • Advancing to May 1st would not make sense in most cases - as we started in March so expected to end in April.
• Now consider February 29th 2020 plus one year. The result cannot be February 29th 2021, because in that year February only has 28 days. Thus, the result is February 28th 2021.
  • Advancing to March 1st 2021 would not make sense in most cases - as we started in February so expected to end in February.

The issue should be closed. Thanks.

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Closing per conversation above.

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