HP-UX Reference (11i v1 00/12) - 3 Library Functions A-M (vol 6)

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STANDARD Printed by: Nora Chuang [nchuang] STANDARD

/build/1111/BRICK/man3/!!!intro.3c

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ctime(3C) ctime(3C)

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 tm_isdst 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 timezone contains the difference, in seconds, between UTC and local standard

time (for example, in the U.S. Eastern time zone (EST), timezone is 5∗60∗60). The external variable

daylight is non-zero only if a summer time zone adjustment is speciﬁed in the TZ environment variable.

The external variable tzname[2] contains the local standard and local summer time zone abbreviations

as speciﬁed by the TZ environment variable.

EXTERNAL INFLUENCES

Locale

The LC_CTYPE category determines the interpretation of the bytes within format as single and/or multi-

byte characters.

Environment Variables

The tzset() function uses the contents of TZ to set the values of the external variables timezone

daylight , and tzname. TZ also determines the time zone name substituted for the %Z and

directives and the time zone adjustments performed by localtime() , mktime(), and ctime().Two

methods for specifying a time zone within

TZ are described in environ(5).

International Code Set Support

Single- and multi-byte character code sets are supported.

RETURN VALUE

For asctime_r() and ctime_r(), if the buffer is of insufﬁcient length, a NULL is returned and

errno set to EINVAL.

asctime_r(), ctime_r(), gmtime_r(), and localtime_r(),

return a NULL and set

errno to EINVAL if NULL pointers are passed in as arguments.

A NULL is returned and errno is set to

ERANGE if the input to the following routines is not within the sup-

ported range: asctime(), asctime_r() , ctime(), ctime_r(), gmtime(), gmtime_r(),

localtime() , localtime_r().

APPLICATION USAGE

The return values for

asctime(), ctime(), gmtime(), and localtime() point to static data

whose contents is overwritten by each call. Thus, these routines are unsafe in multi-thread applications.

asctime_r() , ctime_r(), gmtime_r() , and localtime_r() are thread-safe. These interfaces

are not async-cancel-safe.

WARNINGS

Users of asctime_r() , ctime_r(), gmtime_r() , and localtime_r()

should also note that

these functions now conform to POSIX.1c. The old prototypes of these functions are supported for compati-

bility with existing DCE applicationsonly.

The range of

tm_sec([0,61])

extends to 61 to allow for the occasional one or two leap seconds. How-

ever, the ‘‘seconds since the Epoch’’ value returned by time(2) and passed as the timer argument does not

include accumulated leap seconds. The

tm structure generated by localtime() and gmtime() will

never reﬂect any leap seconds. Upon successful completion, mktime() forces the value of the tm_sec

component to the range [0,59].

AUTHOR

ctime() was developed by AT&T and HP.