S-Lang Run-Time Library Reference: Version 1.4.0: Time and Date Functions

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## 8. Time and Date Functions

## 8.1 _time

Synopsis

  Get the current time in seconds

Usage

  `ULong_Type _time ()`

Description

  The `_time` function returns the number of elapsed seconds since 00:00:00 GMT, January 1, 1970. The `ctime` function may be used to convert this into a string representation.

See Also

  `ctime, time, localtime, gmtime`

## 8.2 ctime

Synopsis

  Convert a calendar time to a string

Usage

  `String_Type ctime(ULong_Type secs)`

Description

  This function returns a string representation of the time as given by `secs` seconds since 1970.

See Also

  `time, _time, localtime, gmtime`

## 8.3 gmtime

Synopsis

  Break down a time in seconds to GMT timezone

Usage

  `Struct_Type gmtime (Long_Type secs)`

Description

  The `gmtime` function is exactly like `localtime` except that the values in the structure it returns are with respect to GMT instead of the local timezone. See the documentation for `localtime` for more information.

Notes

  On systems that do not support the `gmtime` C library function, this function is the same as `localtime`.

See Also

  `localtime, _time`

## 8.4 localtime

Synopsis

  Break down a time in seconds to local timezone

Usage

  `Struct_Type localtime (Long_Type secs)`

Description

  The `localtime` function takes a parameter `secs` representing the number of seconds since 00:00:00, January 1 1970 UTC and returns a structure containing information about `secs` in the local timezone. The structure contains the following `Int_Type` fields:

  `tm_sec` The number of seconds after the minute, normally in the range 0 to 59, but can be up to 61 to allow for leap seconds.

  `tm_min` The number of minutes after the hour, in the range 0 to 59.

  `tm_hour` The number of hours past midnight, in the range 0 to 23.

  `tm_mday` The day of the month, in the range 1 to 31.

  `tm_mon` The number of months since January, in the range 0 to 11.

  `tm_year` The number of years since 1900.

  `tm_wday` The number of days since Sunday, in the range 0 to 6.

  `tm_yday` The number of days since January 1, in the range 0 to 365.

  `tm_isdst` A flag that indicates whether daylight saving time is in effect at the time described. The value is positive if daylight saving time is in effect, zero if it is not, and negative if the information is not available.

See Also

  `gmtime, _time, ctime`

## 8.5 tic

Synopsis

  Start timing

Usage

  `void tic ()`

Description

  The `tic` function restarts the internal clock used for timing the execution of commands. To get the elapsed time of the clock, use the `toc` function.

See Also

  `toc, times`

## 8.6 time

Synopsis

  Return the current data and time as a string

Usage

  `String_Type time ()`

Description

  This function returns the current time as a string of the form:

  > `

  >         Sun Apr 21 13:34:17 1996

  > `

See Also

  `ctime, message, substr`

## 8.7 times

Synopsis

  Get process times

Usage

  `Struct_Type times ()`

Description

  The `times` function returns a structure containing the following fields:

  > `

  >         tms_utime     (user time)
  >         tms_stime     (system time)
  >         tms_cutime    (user time of child processes)
  >         tms_cstime    (system time of child processes)

  > `

Notes

  Not all systems support this function.

See Also

  `tic, toc, _times`

## 8.8 toc

Synopsis

  Get elapsed CPU time

Usage

  `Double_Type toc ()`

Description

  The `toc` function returns the elapsed CPU time in seconds since the last call to `tic`. The CPU time is the amount of time the CPU spent running the code of the current process.

Example

  The `tic` and `toc` functions are ideal for timing the execution of the interpreter:

  > `

  >          variable a = "hello", b = "world", c, n = 100000, t;

  >          tic ();  loop (n) c = a + b; t = toc ();
  >          vmessage ("a+b took %f seconds\n", t);
  >          tic ();  loop (n) c = strcat(a,b); t = toc ();
  >          vmessage ("strcat took %f seconds\n", t);

  > `

Notes

  This function may not be available on all systems.

  The implementation of this function is based upon the `times` system call. The precision of the clock is system dependent.

See Also

  `tic, times, _time`

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