Question: Convert datetime to long number

[Tim Peters]

[John Smith]
>   A probably very simple question. How do I convert a datetime object to
> the long number.  I mean if I do
>
> >>> x=datetime.utcnow(); a=time.time()
> >>> x,a
> (datetime.datetime(2003, 5, 25, 2, 2, 32, 540000), 1053828152.54)
> >>>
>
> what function f I can apply to x such that  f(x) will return 1053828152.54

It's hard to know whether you're asking about ways to convert between time
zones, or asking about how to get a timestamp at all.  Assuming you're
content to work in local time,

>>> x = datetime.now(); a = time.time()
>>> x, a
(datetime.datetime(2003, 5, 25, 12, 12, 15, 830000), 1053879135.83)
>>> time.mktime(x.timetuple())
1053879135.0
>>> _ - a
-0.83000004291534424
>>>

It's missing (only) the microseconds from the kind of timestamp time.time()
returns.  If you want those too, then

>>> time.mktime(x.timetuple()) + x.microsecond / 1e6
1053879135.83
>>> _ - a
0.0
>>>

If you need to work with UTC, then it's similar but more obscure:

>>> x = datetime.utcnow(); a = time.time()
>>> x, a
(datetime.datetime(2003, 5, 25, 16, 24, 45, 730000), 1053879885.73)
>>> calendar.timegm(x.utctimetuple())
1053879885
>>> _ - a
-0.73000001907348633
>>> calendar.timegm(x.utctimetuple()) + x.microsecond / 1e6
1053879885.73
>>> _ - a
0.0
>>>

datetime isn't keen to use floating-point timestamps, because what
1053879135.83 means varies across platforms (not all boxes start counting at
1970, and boxes disagree about whether leap seconds should be counted), and
because a float doesn't have enough bits of precision to represent all the
date+time combinations datetime can represent.  Support for timestamps in
the datetime module is thus minimal -- we're trying to move away from them.

[Gerrit Holl]
> You can use the strftime method, and pass "%s" as entry:
>
> datetime.datetime.utcnow().strftime("%s")
>
> Note that strftime returns an int, not a float.

Sorry, strftime() returns a string, and doesn't have anything to do with
timestamps regardless.  You may be thinking of strptime?