6.2. Built-in Module time

An explanation of some terminology and conventions is in order.

• 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 gmtime(0).

• 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.

• 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.

• 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.

altzone -- data of module time

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 daylight is nonzero.

asctime (tuple) -- function of module time

Convert a tuple representing a time as returned by gmtime() or localtime() to a 24-character string of the following form: 'Sun Jun 20 23:21:05 1993'. Note: unlike the C function of the same name, there is no trailing newline.

clock () -- function of module time

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.

ctime (secs) -- function of module time

Convert a time expressed in seconds since the epoch to a string representing local time. ctime(t) is equivalent to asctime(localtime(t)).

daylight -- data of module time

Nonzero if a DST timezone is defined.

gmtime (secs) -- function of module time

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.

localtime (secs) -- function of module time

Like gmtime but converts to local time. The dst flag is set to 1 when DST applies to the given time.

mktime (tuple) -- function of module time

This is the inverse function of localtime. Its argument is the full 9-tuple (since the dst flag is needed). It returns an integer.

sleep (secs) -- function of module time

Suspend execution for the given number of seconds. The argument may be a floating point number to indicate a more precise sleep time.

strftime (format, tuple) -- function of module time

Convert a tuple representing a time as returned by gmtime() or localtime() to a string as specified by the format argument. See the strftime(3) man page for details of the syntax of format strings.

time () -- function of module 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.

timezone -- data of module time

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).

tzname -- data of module time

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.