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  1. Qt
  2. QTBUG-82886

Qt::DefaultLocaleShortDate / QLocale::ShortFormat date parsing doesn't deal with 4-digit years

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Details

    • Bug
    • Resolution: Unresolved
    • P2: Important
    • None
    • 5.14
    • Core: Date/Time
    • None
    • 21

    Description

      QDate::fromString(QLatin1String("2/3/2020"), Qt::DefaultLocaleShortDate) doesn't work. QDate::fromString(QLatin1String("2/3/20"), Qt::DefaultLocaleShortDate) parses the date as Feb 3, 1920 in an American locale. Yet QLocale().dateFormat(QLocale::ShortFormat) recommends "M/d/yy" as the format to use. The idea of using 2-digit years at all was obsolete more than 20 years ago.

      In Qt 6 we should always use 4-digit years for reading and writing short-format dates.

      If we must support 2-digit years for some reason, we could use a sliding window somehow so that 99 means 1999 and 20 means 2020, but that's a slippery slope to extended bikeshedding about where the boundary should be.

      $ ./dateparse 02/03/99
[     0.000 D] default unknown - acceptable short format "M/d/yy"
[     0.000 D] default unknown - parsed "02/03/99" as "Wed Feb 3 1999"
[     0.000 D] default unknown - parsed 2/3/2020 as ""
[     0.000 D] default unknown - parsed 2/3/20 as "Tue Feb 3 1920"

      Attachments

        Issue Links

          duplicates

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-74323 QDate::from string gives wrong year

          • P2: Important - Urgent, should be fixed, but will not stop the release.
          • Closed
          is duplicated by

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-89147 QDate::fromString() still asumes we're in the 20th century

          • Not Evaluated - Not yet evaluated/prioritized
          • Closed
          relates to

          Epic - Created by Jira Software - do not edit or delete. Issue type for a big user story that needs to be broken down. QTBUG-117055 Implement a generic internal framework for formats for parsing and serializing

          • P3: Somewhat important - Should be fixed, but doesn't affect the release in any way.
          • Open

          Task - A task that needs to be done. QTBUG-77948 Rewrite QDateTimeParser

          • P2: Important - Urgent, should be fixed, but will not stop the release.
          • Open

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-84334 QDate::fromString cannot parse date with negative year

          • P3: Somewhat important - Should be fixed, but doesn't affect the release in any way.
          • Closed

          Suggestion - Public suggestions QTBUG-46843 Way to change base year for QDate::fromString 2 digit year parsing

          • P3: Somewhat important - Should be fixed, but doesn't affect the release in any way.
          • Closed
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          Activity

            People

              Eddy Edward Welbourne
              srutledg Shawn Rutledge
              Vladimir Minenko Vladimir Minenko
              Alex Blasche Alex Blasche
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                Updated:

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