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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Inconsistent `datetime.*.strftime()` year padding behavior across `%y`, `%Y`, `%F` and `%C`","articleBody":"# Bug report\r\n\r\n### Bug description:\r\n\r\n#120713 changed the way `%y` and `%Y` format works with `strftime()` to pad \"short\" years with leading zeros. However, the `%F` and `%C` formats were left alone, creating inconsistency:\r\n\r\n```python\r\n\u003e\u003e\u003e from datetime import date\r\n\u003e\u003e\u003e date(909, 9, 9).strftime(\"%Y\")\r\n'0909'\r\n\u003e\u003e\u003e date(909, 9, 9).strftime(\"%y\")\r\n'09'\r\n\u003e\u003e\u003e date(909, 9, 9).strftime(\"%C\")\r\n'9'\r\n\u003e\u003e\u003e date(909, 9, 9).strftime(\"%F\")\r\n'909-09-09'\r\n```\r\n\r\nWhile I don't have a strong opinion about `%C`, the change to `%Y` now means that `%Y-%m-%d` no longer matches `%F`.\r\n\r\nNotably, this change broke the logic in Django that assumed that if `%Y` returns a zero-padded year number, no padding needs to be done for all formats:\r\n\r\nhttps://github.com/django/django/blob/0e94f292cda632153f2b3d9a9037eb0141ae9c2e/django/utils/formats.py#L266-L273\r\n\r\nI will report a bug there as well, but I think it would be beneficial to preserve consistency here.\r\n\r\nDjango bug: https://code.djangoproject.com/ticket/35630\r\n\r\nCC @blhsing @martinvuyk \r\n\r\n### CPython versions tested on:\r\n\r\n3.13, CPython main branch\r\n\r\n### Operating systems tested on:\r\n\r\nLinux\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-122436\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/mgorny","@type":"Person","name":"mgorny"},"datePublished":"2024-07-25T10:38:28.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":21},"url":"https://github.com/122272/cpython/issues/122272"}