将字符串转换为日期python

Question

I'm following the following guide on how to convert a string into a date object in python but I came across an error that I don't quite understand.

I'm trying to do the following:

buildDateArray.append(dt.strptime(date,"%y-%b-%d %H:%M:%S"))

But I get the bellow error:

    buildDateArray.append(dt.strptime(date,"%y-%b-%d %H:%M:%S"))
  File "/usr/lib64/python2.6/_strptime.py", line 325, in _strptime
    (data_string, format))
ValueError: time data '2014-11-17 00:00:00' does not match format '%y-%b-%d %H:%M:%S'

I don't understand why '2014-11-17 00:00:00' does not match format '%y-%b-%d %H:%M:%S'

Can you see what the error is?

Answer 1

Your format has two problems:

• %y matches a two digit year, but your year contains 4. Use %Y (capital Y ) instead.

• %b matches a named month, abbreviated; use %m instead to match a numeric month; you need to match 11 here, not Nov .

Demo:

>>> from datetime import datetime
>>> datetime.strptime('2014-11-17 00:00:00', '%Y-%m-%d %H:%M:%S')
datetime.datetime(2014, 11, 17, 0, 0)

When you face a problem like this, try to narrow it down to the components; you could have tried just the year part for example, and it'd have failed still, but with a different error giving you a big hint as to why it might be failing:

>>> datetime.strptime('2014', '%y')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/mpietre/Development/Library/buildout.python/parts/opt/lib/python2.7/_strptime.py", line 328, in _strptime
    data_string[found.end():])
ValueError: unconverted data remains: 14

Since you are using the datetime.strptime() class method , you need to look a the correct documentation, found at strftime() and strptime() Behavior ; it details what each pattern matches.

Answer 2

You have two problems with your format

• Use a capital Y to match the four digit year instead of the lower case y (it matches only two digit)
• Use %m instead of %b to match the numeric month instead of the abbreviated month (ie. 11 vs Nov )

Your final format would be:

"%Y-%m-%d %H:%M:%S"