Handle date difference for ends of months #553
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The incrementally calling `Window::Globalization::Calendar::AddMonths` resulted in a negative value for `GetDifferenceInDays` which was then assigned to an unsigned variable `daysDiff`. One example of the issue when running the calculator in UTC+2 was the difference between July 31st and December 30th. The initial guess was 4 months which then landed on November 30th. This date was stored and then in the loop incremeted by one month. This then landed precisely on the end date December 30th. After the loop the final value is then used July 31st + 5 months which results in the 31st of December. The resulting difference of -1 days is then assigned to the unsigned value `daysDiff`. This commit makes the minimal changes to remedy this bug. It makes sure to only ever call `AddMonths` with the same starting date instead of incrementally to different dates. fixes microsoft#552
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Maybe also add a Unit Test that replicates the bug? So it will never appear again! |
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Fixes #552
Description of the changes:
The incrementally calling
Window::Globalization::Calendar::AddMonthsresulted in a negative value for
GetDifferenceInDayswhich was thenassigned to an unsigned variable
daysDiff.One example of the issue when running the calculator in UTC+2 was the
difference between July 31st and December 30th.
The initial guess was 4 months which then landed on November 30th.
This date was stored and then in the loop incremeted by one month.
This then landed precisely on the end date December 30th.
After the loop the final value is then used July 31st + 5 months
which results in the 31st of December.
The resulting difference of -1 days is then assigned to the unsigned
value
daysDiff.This commit makes the minimal changes to remedy this bug.
It makes sure to only ever call
AddMonthswith the same starting dateinstead of incrementally to different dates.
This commit makes the minimal changes to remedy this bug.
It makes sure to only ever call
AddMonthswith the same starting dateinstead of incrementally to different dates.
How changes were validated: