(guile.info.gz) Time

(guile.info.gz) Runtime Environment
 
 38.5 Time
 =========
 
  -- Scheme Procedure: current-time
  -- C Function: scm_current_time ()
      Return the number of seconds since 1970-01-01 00:00:00 UTC,
      excluding leap seconds.
 
  -- Scheme Procedure: gettimeofday
  -- C Function: scm_gettimeofday ()
      Return a pair containing the number of seconds and microseconds
      since 1970-01-01 00:00:00 UTC, excluding leap seconds.  Note:
      whether true microsecond resolution is available depends on the
      operating system.
 
    The following procedures either accept an object representing a
 broken down time and return a selected component, or accept an object
 representing a broken down time and a value and set the component to
 the value.  The numbers in parentheses give the usual range.
 
 `tm:sec, set-tm:sec'
      Seconds (0-59).
 
 `tm:min, set-tm:min'
      Minutes (0-59).
 
 `tm:hour, set-tm:hour'
      Hours (0-23).
 
 `tm:mday, set-tm:mday'
      Day of the month (1-31).
 
 `tm:mon, set-tm:mon'
      Month (0-11).
 
 `tm:year, set-tm:year'
      Year (70-), the year minus 1900.
 
 `tm:wday, set-tm:wday'
      Day of the week (0-6) with Sunday represented as 0.
 
 `tm:yday, set-tm:yday'
      Day of the year (0-364, 365 in leap years).
 
 `tm:isdst, set-tm:isdst'
      Daylight saving indicator (0 for "no", greater than 0 for "yes",
      less than 0 for "unknown").
 
 `tm:gmtoff, set-tm:gmtoff'
      Time zone offset in seconds west of UTC (-46800 to 43200).
 
 `tm:zone, set-tm:zone'
      Time zone label (a string), not necessarily unique.
 
  -- Scheme Procedure: localtime time [zone]
  -- C Function: scm_localtime (time, zone)
      Return an object representing the broken down components of TIME,
      an integer like the one returned by `current-time'.  The time zone
      for the calculation is optionally specified by ZONE (a string),
      otherwise the `TZ' environment variable or the system default is
      used.
 
  -- Scheme Procedure: gmtime time
  -- C Function: scm_gmtime (time)
      Return an object representing the broken down components of TIME,
      an integer like the one returned by `current-time'.  The values
      are calculated for UTC.
 
  -- Scheme Procedure: mktime sbd_time [zone]
  -- C Function: scm_mktime (sbd_time, zone)
      BD-TIME is an object representing broken down time and `zone' is
      an optional time zone specifier (otherwise the TZ environment
      variable or the system default is used).
 
      Returns a pair: the car is a corresponding integer time value like
      that returned by `current-time'; the cdr is a broken down time
      object, similar to as BD-TIME but with normalized values.
 
  -- Scheme Procedure: tzset
  -- C Function: scm_tzset ()
      Initialize the timezone from the TZ environment variable or the
      system default.  It's not usually necessary to call this procedure
      since it's done automatically by other procedures that depend on
      the timezone.
 
  -- Scheme Procedure: strftime format stime
  -- C Function: scm_strftime (format, stime)
      Formats a time specification TIME using TEMPLATE.  TIME is an
      object with time components in the form returned by `localtime' or
      `gmtime'.  TEMPLATE is a string which can include formatting
      specifications introduced by a `%' character.  The formatting of
      month and day names is dependent on the current locale.  The value
      returned is the formatted string.   Formatting Date and Time
      (libc)Formatting Date and Time.)
 
           (strftime "%c" (localtime (current-time)))
           => "Mon Mar 11 20:17:43 2002"
 
  -- Scheme Procedure: strptime format string
  -- C Function: scm_strptime (format, string)
      Performs the reverse action to `strftime', parsing STRING
      according to the specification supplied in TEMPLATE.  The
      interpretation of month and day names is dependent on the current
      locale.  The value returned is a pair.  The car has an object with
      time components in the form returned by `localtime' or `gmtime',
      but the time zone components are not usefully set.  The cdr
      reports the number of characters from STRING which were used for
      the conversion.
 
  -- Variable: internal-time-units-per-second
      The value of this variable is the number of time units per second
      reported by the following procedures.
 
  -- Scheme Procedure: times
  -- C Function: scm_times ()
      Return an object with information about real and processor time.
      The following procedures accept such an object as an argument and
      return a selected component:
 
     `tms:clock'
           The current real time, expressed as time units relative to an
           arbitrary base.
 
     `tms:utime'
           The CPU time units used by the calling process.
 
     `tms:stime'
           The CPU time units used by the system on behalf of the calling
           process.
 
     `tms:cutime'
           The CPU time units used by terminated child processes of the
           calling process, whose status has been collected (e.g., using
           `waitpid').
 
     `tms:cstime'
           Similarly, the CPU times units used by the system on behalf of
           terminated child processes.
 
  -- Scheme Procedure: get-internal-real-time
  -- C Function: scm_get_internal_real_time ()
      Return the number of time units since the interpreter was started.
 
  -- Scheme Procedure: get-internal-run-time
  -- C Function: scm_get_internal_run_time ()
      Return the number of time units of processor time used by the
      interpreter.  Both _system_ and _user_ time are included but
      subprocesses are not.
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