ctime(3C) ctime(3C)
NAME
ctime(), ctime_r(), asctime(), asctime_r(), daylight(), difftime(), gmtime(), gmtime_r(), localtime(), localtime_r(), mktime(), timezone(),
tzname(), tzset() - convert date and time to string
SYNOPSIS
DESCRIPTION
Convert the broken-down time contained in the structure pointed to by
timeptr and return a pointer to a 26-character string in the form:
All the fields have constant width.
returns NULL and sets errno to if tm_year in is less than 0 or is greater than 8099. In both 32-bit and 64-bit HP-UX,
the minimum date supported by is January 1 00:00:00 1900 and the maximum date supported by is December 31 23:59:59 9999.
is identical to except that it places the result in the user supplied and returns a pointer to upon success. A buffer length of at least
26 is required.
Convert the calendar time pointed to by
timer, representing the time in seconds since the Epoch, and return a pointer to the local time in the form of a string.
Equivalent to:
The minimum date supported by in both 32-bit and 64-bit HP-UX is Friday December 13 20:45:52 UTC 1901. The maximum dates
supported by are Tuesday January 19 03:14:07 UTC 2038 and Friday December 31 23:59:59 UTC 9999 in 32-bit HP-UX and 64-bit
HP-UX, respectively.
In 64-bit HP-UX, returns NULL and sets errno to if timer is less than the number of seconds that corresponds to the mini-
mum date supported (i.e., as defined in or exceeds the number of seconds that corresponds to the maximum date supported.
is identical to except that it places the result in the user supplied and returns a pointer to upon success. A buffer length of at least
26 is required.
Return the difference in seconds between two calendar times:
time1 - time0.
Convert directly to Coordinated Universal Time (UTC),
the time standard used by the HP-UX operating system. returns a pointer to the structure described below.
The minimum date supported by in both 32-bit and 64-bit HP-UX is Friday December 13 20:45:52 UTC 1901. The maximum dates
supported by are Tuesday January 19 03:14:07 UTC 2038 and Friday December 31 23:59:59 UTC 9999 in 32-bit HP-UX and 64-bit
HP-UX, respectively.
In 64-bit HP-UX, returns NULL and sets errno to if timer is less than the number of seconds that corresponds to the mini-
mum date supported (i.e., as defined in or exceeds the number of seconds that corresponds to the maximum date supported.
is identical to except that stores the result in the pointed to by and returns upon success.
Correct for the time zone and any summer time zone adjustments
(such as Daylight Savings Time in the USA), according to the contents of the environment variable (see below). returns a
pointer to the structure described below.
The minimum date supported by in both 32-bit and 64-bit HP-UX is Friday December 13 20:45:52 UTC 1901. The maximum dates
supported by are Tuesday January 19 03:14:07 UTC 2038 and Friday December 31 23:59:59 UTC 9999 in 32-bit HP-UX and 64-bit
HP-UX, respectively.
In 64-bit HP-UX, returns NULL and sets errno to if timer is less than the number of seconds that corresponds to the mini-
mum date supported (i.e., as defined in or exceeds the number of seconds that corresponds to the maximum date supported.
is identical to except that stores the result in the pointed to by and returns upon success.
Convert the broken-down time (expressed as local time)
in the structure pointed to by timeptr into a calendar time value with the same encoding as that of the values returned
by The original values of the and components of the structure are ignored, and the original values of the other compo-
nents are not restricted to the ranges indicated below.
A positive or zero value for causes to initially presume that Daylight Saving Time respectively is or is not in effect
for the specified time. A negative value for causes to attempt to determine whether Daylight Saving Time is in effect
for the specified time.
Upon successful completion, all the components are set to represent the specified calendar time, but with their values
forced to the ranges indicated below. The final value of is not set until and are determined. returns the specified
calendar time encoded as a value of type
The minimum date supported by in both 32-bit and 64-bit HP-UX is Friday December 13 20:45:52 UTC 1901. The maximum dates
supported by are Tuesday January 19 03:14:07 UTC 2038 and Friday December 31 23:59:59 UTC 9999 in 32-bit HP-UX and 64-bit
HP-UX, respectively.
For 32-bit if the calendar time cannot be represented, the function returns the value and sets to Note the value also
corresponds to the time 23:59:59 on Dec 31, 1969 (plus or minus time zone and Daylight Saving Time adjustments). Thus it
is necessary to check both the return value and to reliably detect an error condition.
The behavior of 64-bit beyond the supported ranges is undefined.
Sets the values of the external variables
timezone, daylight, and tzname according to the contents of the environment variable (independent of any time value).
The functions and (see strftime(3C)) call and use the values returned in the external variables described below for their
operations. can also be called directly by the user.
When the environment variable is not set, checks the default file for the timezone value and sets timezone values based
on that. The file contains the timezone value used by when the environment variable is not set. The format for the file
is same as format without the prefix Please check environ(5) for format.
If the value of the timezone cannot be determined using the environment variable or the file it is set to the default
value of EST5EDT. If the timezone is set to the default value of EST5EDT and the timezone adjustment file is not avail-
able, the timezone is set to a default value of UTC (Coordinated Universal Time).
can be modified for an appropriate default value for timezone.
The header file contains declarations of all relevant functions and externals. It also contains the structure, which includes the follow-
ing members:
int tm_sec; /* seconds after the minute - [0,61] */
int tm_min; /* minutes after the hour - [0,59] */
int tm_hour; /* hours - [0,23] */
int tm_mday; /* day of month - [1,31] */
int tm_mon; /* month of year - [0,11] */
int tm_year; /* years since 1900 */
int tm_wday; /* days since Sunday - [0,6] */
int tm_yday; /* days since January 1 - [0,365] */
int tm_isdst; /* daylight savings time flag */
The value of is positive if a summer time zone adjustment such as Daylight Savings Time is in effect, zero if not in effect, and negative
if the information is not available.
The external variable contains the difference, in seconds, between UTC and local standard time (for example, in the U.S. Eastern time zone
(EST), is 5*60*60). The external variable is non-zero only if a summer time zone adjustment is specified in the environment variable. The
external variable contains the local standard and local summer time zone abbreviations as specified by the environment variable.
EXTERNAL INFLUENCES
Locale
The category determines the interpretation of the bytes within format as single and/or multi-byte characters.
Environment Variables
The function uses the contents of to set the values of the external variables and also determines the time zone name substituted for the
and directives and the time zone adjustments performed by and Two methods for specifying a time zone within are described in environ(5).
International Code Set Support
Single and multibyte character code sets are supported.
RETURN VALUE
For and if the buffer is of insufficient length, a NULL is returned and errno set to
and return a NULL and set errno to if NULL pointers are passed in as arguments.
A NULL is returned and errno is set to if the input to the following routines is not within the supported range:
APPLICATION USAGE
The return values for and point to static data whose contents is overwritten by each call.
WARNINGS
Users of and should also note that these functions now conform to POSIX.1c. The old prototypes of these functions are supported for compat-
ibility with existing DCE applications only.
The range of extends to 61 to allow for the occasional one or two leap seconds. However, the "seconds since the Epoch" value returned by
(see time(2)) and passed as the timer argument does not include accumulated leap seconds. The structure generated by and will never
reflect any leap seconds. Upon successful completion, forces the value of the component to the range [0,59].
AUTHOR
was developed by AT&T and HP.
SEE ALSO
time(2), getdate(3C), setlocale(3C), strftime(3C), tztab(4), environ(5), lang(5), langinfo(5), thread_safety(5).
STANDARDS CONFORMANCE
ctime(3C)