import datetime
# this will fail
datetime.datetime.strptime('2025-10-26','%F') 
# this will succeed
d0 = datetime.datetime.strptime('15:00:00','%T') 
print(d0.strftime('%FT%T'))

Example above ('%F', C99+ time.h format token) requires simple fix in the code; requires larger alignment in documentation.

Example Code Patch

To support '%F' in strptime requires adding a single line of code. The example above is fixed with the following line added to the TimeRE class __init__ method in Lib/_strptime.py,

base.__setitem__('F', self.pattern('%Y-%m-%d'))

just like existing code in that method for %T support (https://github.com/python/cpython/blob/main/Lib/_strptime.py#L421)

Documentation

The documentation refers to C89 (https://github.com/python/cpython/blob/main/Doc/library/datetime.rst?plain=1#L2498-L2636) and does not fully document the current level of strptime support.

Final thoughts

A larger discussion should be had on modernizing datetime and fully supporting C99 (ideally newer) time.h format tokens.

Linked PRs

• gh-140715: provide support for %F token in strptime; add test for it and %T #140647