parent
4e6688747c
commit
2cfc835b7b
|
@ -1,7 +1,7 @@
|
|||
\section{Built-in Module \sectcode{time}}
|
||||
\label{module-time}
|
||||
|
||||
\bimodindex{time}
|
||||
|
||||
This module provides various time-related functions.
|
||||
It is always available.
|
||||
|
||||
|
@ -10,19 +10,24 @@ 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
|
||||
\index{epoch}
|
||||
The \dfn{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
|
||||
\index{UTC}
|
||||
\index{Coordinated Universal Time}
|
||||
\index{Greenwich Mean Time}
|
||||
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
|
||||
\index{Daylight Saving Time}
|
||||
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
|
||||
(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.
|
||||
|
@ -34,31 +39,30 @@ 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.
|
||||
|
||||
\item
|
||||
On the other hand, the precision of \code{time()} and \code{sleep()}
|
||||
is better than their \UNIX{} equivalents: times are expressed as floating
|
||||
point numbers, \code{time()} returns the most accurate time available
|
||||
(using \UNIX{} \code{gettimeofday()} where available), and \code{sleep()}
|
||||
will accept a time with a nonzero fraction (\UNIX{} \code{select()} is
|
||||
used to implement this, where available).
|
||||
On the other hand, the precision of \function{time()} and
|
||||
\function{sleep()} is better than their \UNIX{} equivalents: times are
|
||||
expressed as floating point numbers, \function{time()} returns the
|
||||
most accurate time available (using \UNIX{} \cfunction{gettimeofday()}
|
||||
where available), and \function{sleep()} will accept a time with a
|
||||
nonzero fraction (\UNIX{} \cfunction{select()} is used to implement
|
||||
this, where available).
|
||||
|
||||
\item
|
||||
The time tuple as returned by \code{gmtime()} and \code{localtime()},
|
||||
or as accpted by \code{mktime()} is a tuple of 9
|
||||
integers: 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) and daylight savings flag (-1, 0 or 1).
|
||||
Note that unlike the C structure, the month value is a range of 1-12, not
|
||||
The time tuple as returned by \function{gmtime()} and
|
||||
\function{localtime()}, or as accpted by \function{mktime()} is a
|
||||
tuple of 9 integers: 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) and daylight savings flag (-1, 0 or 1).
|
||||
Note that unlike the \C{} structure, the month value is a range of 1-12, not
|
||||
0-11. A year value less than 100 will typically be silently converted to
|
||||
1900 plus the year value. A -1 argument as daylight savings flag, passed to
|
||||
\code{mktime()} will usually result in the correct daylight savings
|
||||
state to be filled in.
|
||||
|
||||
1900 plus the year value. A \code{-1} argument as daylight savings
|
||||
flag, passed to \function{mktime()} will usually result in the correct
|
||||
daylight savings state to be filled in.
|
||||
|
||||
\end{itemize}
|
||||
|
||||
The module defines the following functions and data items:
|
||||
|
||||
\setindexsubitem{(in module time)}
|
||||
|
||||
\begin{datadesc}{altzone}
|
||||
The offset of the local DST timezone, in seconds west of the 0th
|
||||
|
@ -77,15 +81,15 @@ the same name, there is no trailing newline.
|
|||
\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,
|
||||
but in any case, this is the function to use for benchmarking Python
|
||||
or timing algorithms.
|
||||
of ``CPU time''\index{CPU time}, depends on that of the \C{} function
|
||||
of the same name, but in any case, this is the function to use for
|
||||
benchmarking\index{benchmarking} Python or timing algorithms.
|
||||
\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))}.
|
||||
representing local time. \code{ctime(\var{secs})} is equivalent to
|
||||
\code{asctime(localtime(\var{secs}))}.
|
||||
\end{funcdesc}
|
||||
|
||||
\begin{datadesc}{daylight}
|
||||
|
@ -99,17 +103,18 @@ ignored.
|
|||
\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.
|
||||
Like \function{gmtime()} but converts to local time. The dst flag is
|
||||
set to \code{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 --- pass -1 as the dst flag if
|
||||
it is unknown) which expresses the time
|
||||
full 9-tuple (since the dst flag is needed --- pass \code{-1} as the
|
||||
dst flag if it is unknown) which expresses the time
|
||||
in \emph{local} time, not UTC. 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.
|
||||
point number, for compatibility with \function{time()}. If the input
|
||||
value cannot be represented as a valid time, \exception{OverflowError}
|
||||
is raised.
|
||||
\end{funcdesc}
|
||||
|
||||
\begin{funcdesc}{sleep}{secs}
|
||||
|
@ -157,9 +162,9 @@ Additional directives may be supported on certain platforms, but
|
|||
only the ones listed here have a meaning standardized by ANSI C.
|
||||
|
||||
On some platforms, an optional field width and precision
|
||||
specification can immediately follow the initial \% of a
|
||||
specification can immediately follow the initial \code{\%} of a
|
||||
directive in the following order; this is also not portable.
|
||||
The field width is normally 2 except for \%j where it is 3.
|
||||
The field width is normally 2 except for \code{\%j} where it is 3.
|
||||
|
||||
\end{funcdesc}
|
||||
|
||||
|
|
|
@ -1,7 +1,7 @@
|
|||
\section{Built-in Module \sectcode{time}}
|
||||
\label{module-time}
|
||||
|
||||
\bimodindex{time}
|
||||
|
||||
This module provides various time-related functions.
|
||||
It is always available.
|
||||
|
||||
|
@ -10,19 +10,24 @@ 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
|
||||
\index{epoch}
|
||||
The \dfn{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
|
||||
\index{UTC}
|
||||
\index{Coordinated Universal Time}
|
||||
\index{Greenwich Mean Time}
|
||||
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
|
||||
\index{Daylight Saving Time}
|
||||
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
|
||||
(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.
|
||||
|
@ -34,31 +39,30 @@ 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.
|
||||
|
||||
\item
|
||||
On the other hand, the precision of \code{time()} and \code{sleep()}
|
||||
is better than their \UNIX{} equivalents: times are expressed as floating
|
||||
point numbers, \code{time()} returns the most accurate time available
|
||||
(using \UNIX{} \code{gettimeofday()} where available), and \code{sleep()}
|
||||
will accept a time with a nonzero fraction (\UNIX{} \code{select()} is
|
||||
used to implement this, where available).
|
||||
On the other hand, the precision of \function{time()} and
|
||||
\function{sleep()} is better than their \UNIX{} equivalents: times are
|
||||
expressed as floating point numbers, \function{time()} returns the
|
||||
most accurate time available (using \UNIX{} \cfunction{gettimeofday()}
|
||||
where available), and \function{sleep()} will accept a time with a
|
||||
nonzero fraction (\UNIX{} \cfunction{select()} is used to implement
|
||||
this, where available).
|
||||
|
||||
\item
|
||||
The time tuple as returned by \code{gmtime()} and \code{localtime()},
|
||||
or as accpted by \code{mktime()} is a tuple of 9
|
||||
integers: 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) and daylight savings flag (-1, 0 or 1).
|
||||
Note that unlike the C structure, the month value is a range of 1-12, not
|
||||
The time tuple as returned by \function{gmtime()} and
|
||||
\function{localtime()}, or as accpted by \function{mktime()} is a
|
||||
tuple of 9 integers: 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) and daylight savings flag (-1, 0 or 1).
|
||||
Note that unlike the \C{} structure, the month value is a range of 1-12, not
|
||||
0-11. A year value less than 100 will typically be silently converted to
|
||||
1900 plus the year value. A -1 argument as daylight savings flag, passed to
|
||||
\code{mktime()} will usually result in the correct daylight savings
|
||||
state to be filled in.
|
||||
|
||||
1900 plus the year value. A \code{-1} argument as daylight savings
|
||||
flag, passed to \function{mktime()} will usually result in the correct
|
||||
daylight savings state to be filled in.
|
||||
|
||||
\end{itemize}
|
||||
|
||||
The module defines the following functions and data items:
|
||||
|
||||
\setindexsubitem{(in module time)}
|
||||
|
||||
\begin{datadesc}{altzone}
|
||||
The offset of the local DST timezone, in seconds west of the 0th
|
||||
|
@ -77,15 +81,15 @@ the same name, there is no trailing newline.
|
|||
\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,
|
||||
but in any case, this is the function to use for benchmarking Python
|
||||
or timing algorithms.
|
||||
of ``CPU time''\index{CPU time}, depends on that of the \C{} function
|
||||
of the same name, but in any case, this is the function to use for
|
||||
benchmarking\index{benchmarking} Python or timing algorithms.
|
||||
\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))}.
|
||||
representing local time. \code{ctime(\var{secs})} is equivalent to
|
||||
\code{asctime(localtime(\var{secs}))}.
|
||||
\end{funcdesc}
|
||||
|
||||
\begin{datadesc}{daylight}
|
||||
|
@ -99,17 +103,18 @@ ignored.
|
|||
\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.
|
||||
Like \function{gmtime()} but converts to local time. The dst flag is
|
||||
set to \code{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 --- pass -1 as the dst flag if
|
||||
it is unknown) which expresses the time
|
||||
full 9-tuple (since the dst flag is needed --- pass \code{-1} as the
|
||||
dst flag if it is unknown) which expresses the time
|
||||
in \emph{local} time, not UTC. 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.
|
||||
point number, for compatibility with \function{time()}. If the input
|
||||
value cannot be represented as a valid time, \exception{OverflowError}
|
||||
is raised.
|
||||
\end{funcdesc}
|
||||
|
||||
\begin{funcdesc}{sleep}{secs}
|
||||
|
@ -157,9 +162,9 @@ Additional directives may be supported on certain platforms, but
|
|||
only the ones listed here have a meaning standardized by ANSI C.
|
||||
|
||||
On some platforms, an optional field width and precision
|
||||
specification can immediately follow the initial \% of a
|
||||
specification can immediately follow the initial \code{\%} of a
|
||||
directive in the following order; this is also not portable.
|
||||
The field width is normally 2 except for \%j where it is 3.
|
||||
The field width is normally 2 except for \code{\%j} where it is 3.
|
||||
|
||||
\end{funcdesc}
|
||||
|
||||
|
|
Loading…
Reference in New Issue