➜  ~ cat dt.py 
from datetime import *
dt = datetime.strptime('+1720', '%z')
print(dt)
➜  ~ python2 dt.py 
Traceback (most recent call last):
  File "dt.py", line 2, in <module>
    dt = datetime.strptime('+1720', '%z')
  File "/usr/lib/python2.7/_strptime.py", line 324, in _strptime
    (bad_directive, format))
ValueError: 'z' is a bad directive in format '%z'
➜  ~ python3 dt.py
1900-01-01 00:00:00+17:20

We should either mention it in doc, either cherry-pick the code from python3

This almost qualifies as a FAQ :)

In 2.7 (and in 3.x, though we've added some additional platform independent stuff there), strptime supports what the platform supports, and this is documented: "The following is a list of all the format codes that the C standard (1989 version) requires, and these work on all platforms with a standard C implementation. Note that the 1999 version of the C standard added additional format codes."

Windows, for one, is not a standard C implementation in that sense.

Note that the python3 documentation is a bit clearer about this than the 2.7 docs.  If you want to open a PR to backport the doc improvements, feel free to reopen this issue.

Neither documentation is clear on whether each of those flags are available for strptime too. A precision should be added on a flag if it's not available for strptime. What do you think ?