mirror of https://github.com/python/cpython
124 lines
4.4 KiB
TeX
124 lines
4.4 KiB
TeX
\section{Built-in Module \sectcode{time}}
|
|
|
|
\bimodindex{time}
|
|
This module provides various time-related functions.
|
|
It is always available.
|
|
|
|
An explanation of some terminology and conventions is in order.
|
|
|
|
\begin{itemize}
|
|
|
|
\item
|
|
The ``epoch'' is the point where the time starts. On January 1st of that
|
|
year, at 0 hours, the ``time since the epoch'' is zero. For UNIX, the
|
|
epoch is 1970. To find out what the epoch is, look at \code{gmtime(0)}.
|
|
|
|
\item
|
|
UTC is Coordinated Universal Time (formerly known as Greenwich Mean
|
|
Time). The acronym UTC is not a mistake but a compromise between
|
|
English and French.
|
|
|
|
\item
|
|
DST is Daylight Saving Time, an adjustment of the timezone by
|
|
(usually) one hour during part of the year. DST rules are magic
|
|
(determined by local law) and can change from year to year. The C
|
|
library has a table containing the local rules (often it is read from
|
|
a system file for flexibility) and is the only source of True Wisdom
|
|
in this respect.
|
|
|
|
\item
|
|
The precision of the various real-time functions may be less than
|
|
suggested by the units in which their value or argument is expressed.
|
|
E.g.\ on most UNIX systems, the clock ``ticks'' only 50 or 100 times a
|
|
second, and on the Mac, times are only accurate to whole seconds.
|
|
|
|
\end{itemize}
|
|
|
|
The module defines the following functions and data items:
|
|
|
|
\renewcommand{\indexsubitem}{(in module time)}
|
|
|
|
\begin{datadesc}{altzone}
|
|
The offset of the local DST timezone, in seconds west of the 0th
|
|
meridian, if one is defined. Negative if the local DST timezone is
|
|
east of the 0th meridian (as in Western Europe, including the UK).
|
|
Only use this if \code{daylight} is nonzero.
|
|
\end{datadesc}
|
|
|
|
|
|
\begin{funcdesc}{asctime}{tuple}
|
|
Convert a tuple representing a time as returned by \code{gmtime()} or
|
|
\code{localtime()} to a 24-character string of the following form:
|
|
\code{'Sun Jun 20 23:21:05 1993'}. Note: unlike the C function of
|
|
the same name, there is no trailing newline.
|
|
\end{funcdesc}
|
|
|
|
|
|
\begin{funcdesc}{clock}{}
|
|
Return the current CPU time as a floating point number expressed in
|
|
seconds. The precision, and in fact the very definiton of the meaning
|
|
of ``CPU time'', depends on that of the C function of the same name.
|
|
\end{funcdesc}
|
|
|
|
|
|
\begin{funcdesc}{ctime}{secs}
|
|
Convert a time expressed in seconds since the epoch to a string
|
|
representing local time. \code{ctime(t)} is equivalent to
|
|
\code{asctime(localtime(t))}.
|
|
\end{funcdesc}
|
|
|
|
\begin{datadesc}{daylight}
|
|
Nonzero if a DST timezone is defined.
|
|
\end{datadesc}
|
|
|
|
\begin{funcdesc}{gmtime}{secs}
|
|
Convert a time expressed in seconds since the epoch to a tuple of 9
|
|
integers, in UTC: year (e.g.\ 1993), month (1--12), day (1--31), hour
|
|
(0--23), minute (0--59), second (0--59), weekday (0--6, monday is 0),
|
|
Julian day (1--366), dst flag (always zero). Fractions of a second are
|
|
ignored. Note subtle differences with the C function of this name.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{localtime}{secs}
|
|
Like \code{gmtime} but converts to local time. The dst flag is set
|
|
to 1 when DST applies to the given time.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{mktime}{tuple}
|
|
This is the inverse function of \code{localtime}. Its argument is the
|
|
full 9-tuple (since the dst flag is needed). It returns a floating
|
|
point number, for compatibility with \code{time.time()}. If the input
|
|
value can't be represented as a valid time, OverflowError is raised.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{sleep}{secs}
|
|
Suspend execution for the given number of seconds. The argument may
|
|
be a floating point number to indicate a more precise sleep time.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{strftime}{format, tuple}
|
|
Convert a tuple representing a time as returned by \code{gmtime()} or
|
|
\code{localtime()} to a string as specified by the format argument.
|
|
See the \code{strftime(3)} man page for details of the syntax of
|
|
format strings.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{time}{}
|
|
Return the time as a floating point number expressed in seconds since
|
|
the epoch, in UTC. Note that even though the time is always returned
|
|
as a floating point number, not all systems provide time with a better
|
|
precision than 1 second.
|
|
\end{funcdesc}
|
|
|
|
\begin{datadesc}{timezone}
|
|
The offset of the local (non-DST) timezone, in seconds west of the 0th
|
|
meridian (i.e. negative in most of Western Europe, positive in the US,
|
|
zero in the UK).
|
|
\end{datadesc}
|
|
|
|
\begin{datadesc}{tzname}
|
|
A tuple of two strings: the first is the name of the local non-DST
|
|
timezone, the second is the name of the local DST timezone. If no DST
|
|
timezone is defined, the second string should not be used.
|
|
\end{datadesc}
|