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strptime: use %r in error messages, not %s #141540
Description
Bug report
Bug description:
Consider the following example, say I'm parsing a date string read from an external source, and I forgot to call .strip():
from datetime import datetime
datetime.strptime("2001-02-03\n", "%Y-%m-%d")The output is a little confusing:
$ python3 strptime_example.py
Traceback (most recent call last):
File "strptime_example.py", line 3, in <module>
datetime.strptime("2025-11-14\n", "%Y-%m-%d")
~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Library/Frameworks/Python.framework/Versions/3.13/lib/python3.13/_strptime.py", line 789, in _strptime_datetime
tt, fraction, gmtoff_fraction = _strptime(data_string, format)
~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^
File "/Library/Frameworks/Python.framework/Versions/3.13/lib/python3.13/_strptime.py", line 558, in _strptime
raise ValueError("unconverted data remains: %s" %
data_string[found.end():])
ValueError: unconverted data remains:
The error message is using %s, when using %r would give a more unambiguous description of the extra data – similar with strings quoted manually using ' in the error message just above:
Lines 567 to 570 in a486d45
CPython versions tested on:
3.13
Operating systems tested on:
macOS
Activity
gvanrossum commentedon Nov 14, 2025
@alexwlchan - Can you find other places with a similar issue? Can you submit a fix for multiple places? The fix is trivial so it should be easy for you to submit a PR (make sure to reference this one).
use %r instead of %s in error messages python#141540
pythongh-141540: Quote the %:z error message with !r as well
pythongh-141540: Quote the colon error message with !r as well
gh-141540: Quote unconverted data in `strptime` error messages (#157832)