I have a time in UTC from which I want the number of seconds since epoch.
I am using strftime to convert it to the number of seconds. Taking 1st April 2012 as an example.
>>>datetime.datetime(2012,04,01,0,0).strftime('%s')
'1333234800'
1st of April 2012 UTC from epoch is 1333238400 but this above returns 1333234800 which is different by 1 hour.
So it looks like that strftime is taking my system time into account and applies a timezone shift somewhere. I thought datetime was purely naive?
How can I get around that? If possible avoiding to import other libraries unless standard. (I have portability concerns).
In Python 3.3+ you can use timestamp():
>>> datetime.datetime(2012,4,1,0,0).timestamp()
1333234800.0
In Python 3.2 or earlier, you could do it explicitly:
>>> (datetime.datetime(2012,4,1,0,0) - datetime.datetime(1970,1,1)).total_seconds()
1333238400.0
Why you should not use datetime.strftime('%s')
Python doesn't actually support %s as an argument to strftime (if you check at http://docs.python.org/library/datetime.html#strftime-and-strptime-behavior it's not in the list), the only reason it's working is because Python is passing the information to your system's strftime, which uses your local timezone.
>>> datetime.datetime(2012,04,01,0,0).strftime('%s')
'1333234800'