Claude
5faa57bb2d
Co-Authored-By: Claude Sonnet 5.5 <[email protected]> Claude-Session: https://claude.ai/code/session_017ic4b3fvyFpxThdRxcozLx
36 lines
1.6 KiB
Plaintext
36 lines
1.6 KiB
Plaintext
== one date, two letters ==
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date = 2026-12-29 (TUESDAY)
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dd-MM-yyyy = 29-12-2026
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dd-MM-YYYY = 29-12-2027
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== the same YYYY pattern, four locales, three dates ==
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date en_US en_GB fr_FR en_IN
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2026-12-28 2027 2026 2026 2027
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2026-12-29 2027 2026 2026 2027
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2027-01-01 2027 2026 2026 2027
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== why: each locale defines what a week is (WeekFields) ==
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en_US WeekFields[SUNDAY,1] week-based-year of 2026-12-29 = 2027, week number = 1
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en_GB WeekFields[MONDAY,4] week-based-year of 2026-12-29 = 2026, week number = 53
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fr_FR WeekFields[MONDAY,4] week-based-year of 2026-12-29 = 2026, week number = 53
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en_IN WeekFields[SUNDAY,1] week-based-year of 2026-12-29 = 2027, week number = 1
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== how often is YYYY wrong? every day of 2020-2030, compared with yyyy ==
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en_US 36 wrong days out of 4018
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en_GB 19 wrong days out of 4018
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fr_FR 19 wrong days out of 4018
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en_IN 36 wrong days out of 4018
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== the days that are wrong in the US locale ==
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2024/2025: 2024-12-29->2025, 2024-12-30->2025, 2024-12-31->2025
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2025/2026: 2025-12-28->2026, 2025-12-29->2026, 2025-12-30->2026, 2025-12-31->2026
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2026/2027: 2026-12-27->2027, 2026-12-28->2027, 2026-12-29->2027, 2026-12-30->2027, 2026-12-31->2027
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2027/2028: 2027-12-26->2028, 2027-12-27->2028, 2027-12-28->2028, 2027-12-29->2028, 2027-12-30->2028, 2027-12-31->2028
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2028/2029: 2028-12-31->2029
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== yyyy vs uuuu: same for modern dates, different for the era ==
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date = -0043-03-15
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yyyy = 0044
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uuuu = -0043
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yyyy G = 0044 BC
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