From 54afa5504cfbe192f5466ff9edc291b10736dfdd Mon Sep 17 00:00:00 2001 From: Alexander Belopolsky Date: Mon, 25 Apr 2011 13:00:40 -0400 Subject: Issue #2736: Documented how to compute seconds since epoch. --- Doc/library/datetime.rst | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/Doc/library/datetime.rst b/Doc/library/datetime.rst index de9ad44..c637f6a 100644 --- a/Doc/library/datetime.rst +++ b/Doc/library/datetime.rst @@ -721,6 +721,22 @@ Other constructors, all class methods: It's common for this to be restricted to years in 1970 through 2038. See also :meth:`fromtimestamp`. + On the POSIX compliant platforms, ``utcfromtimestamp(timestamp)`` + is equivalent to the following expression:: + + datetime(1970, 1, 1) + timedelta(seconds=timestamp) + + There is no method to obtain the timestamp from a :class:`datetime` + instance, but POSIX timestamp corresponding to a :class:`datetime` + instance ``dt`` can be easily calculated as follows. For a naive + ``dt``:: + + timestamp = (dt - datetime(1970, 1, 1)) / timedelta(seconds=1) + + And for an aware ``dt``:: + + timestamp = (dt - datetime(1970, 1, 1, tzinfo=timezone.utc)) / timedelta(seconds=1) + .. classmethod:: datetime.fromordinal(ordinal) -- cgit v0.12