According to https://docs.python.org/3/library/datetime.html, %f is zero-padded on the left. But actual Python 3 behavior is puts the zero padding on the right.

Note: strftime follows the existing documentation:

>>> datetime.datetime(1970, 1, 1, microsecond=1).strftime('%f')
'000001'

The strptime behavior bug seems like a duplicate of #32267, which claims to be fixed in master as of early January; may not have made it into a release yet though. I can't figure out how to view the patch on that issue, it doesn't seem to be linked to GitHub like normal.

I don't believe this is a duplicate if #32267, which is actually about the %z directive.

I think the implementation here is correct and the documentation is semi-correct, it depends on how you look at it, consider:

>>> datetime(2018, 1, 1, 0, 0, 0, 1).strftime('%f')
'000001'

>>> datetime(2018, 1, 1, 0, 0, 0, 100000).strftime('%f')
'100000'

In the first case "1" got expanded to "000001" and "100000" was printed as-is. However, when you interpret it as being *after* the decimal point, you would consider the first one to not be zero-padded at all and the second one to be zero-padded on the right.

I think the documentation can just be changed to "zero-padded to 6 digits" without specifying left or right.

I have made a PR into the repository, can anyone please review and merge it.

New changeset f97ec09baf8431494fd2ef5133090c7b0afd0551 by Vishal Pandey in branch 'main':
bpo-33381: [doc] strftime's %f option may pad zeros on the left or the right (GH-29801)
https://github.com/python/cpython/commit/f97ec09baf8431494fd2ef5133090c7b0afd0551

New changeset 39751420b363530ef46506f10691d7b91ffe9b44 by Miss Islington (bot) in branch '3.10':
bpo-33381: [doc] strftime's %f option may pad zeros on the left or the right (GH-29801) (GH-29862)
https://github.com/python/cpython/commit/39751420b363530ef46506f10691d7b91ffe9b44

New changeset 031e2bb3326be542b224bbe35e7829846ea422cd by Miss Islington (bot) in branch '3.9':
bpo-33381: [doc] strftime's %f option may pad zeros on the left or the right (GH-29801) (GH-29863)
https://github.com/python/cpython/commit/031e2bb3326be542b224bbe35e7829846ea422cd

Thank you Judy and Vishal!

stage: patch review -> resolved

pull_requests: + pull_request28035
stage: patch review

assignee: docs@python
versions: + Python 3.9, Python 3.10, Python 3.11, - Python 3.6
components: + Documentation, Library (Lib)
keywords: + easy, newcomer friendly