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

ManualsBrandsHP ManualsSoftwareHP-UX Reference Manuals

141

142

143

144

145

146

147

148

149

150

__________________________________________________________________________________________________________________________________________________________________________________________________

STANDARD Printed by: Nora Chuang [nchuang] STANDARD

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

________________________________________________________________

___ ___

ctime(3C) ctime(3C)

The minimum date supported by gmtime() in both 32-bit and 64-bit HP-UX is Friday

December 13 20:45:52 UTC 1901. The maximum dates supported by gmtime() 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, gmtime() returns NULL and sets errno to ERANGE if timer is less

than the number of seconds that corresponds to the minimum date supported (i.e.,

INT_MIN, as deﬁned in limits.h), or exceeds the number of seconds that

corresponds to the maximum date supported.

gmtime_r() is identical to gmtime(), except that gmtime_r() stores the result in the tm

struct

pointed to by result and returns result upon success.

localtime() 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 TZ environment variable (see

Environment Variables below). localtime() returns a pointer to the tm structure

described below.

The minimum date supported by localtime() in both 32-bit and 64-bit HP-UX is

Friday December 13 20:45:52 UTC 1901. The maximum dates supported by

local-

time()

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-bitHP-UX, respectively.

In 64-bit HP-UX, localtime() returns NULL and sets errno to ERANGE if timer is

less than the number of seconds that corresponds to the minimum date supported (i.e.,

INT_MIN, as deﬁned in limits.h), or exceeds the number of seconds that

corresponds to the maximum date supported.

localtime_r()

is identical to localtime(), except that localtime_r()

stores the result in the

tm struct pointed to by result and returns result upon success.

difftime() Return the difference in seconds between two calendar times: time1 − time0.

mktime() 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 time(2). The original values of the tm_wday and tm_yday components

of the structure are ignored, and the original values of the other components are not

restricted to the ranges indicated below.

A positive or zero value for tm_isdst causes mktime() to initially presume that

Daylight Saving Time respectively is or is not in effect for the speciﬁed time. A negative

value for tm_isdst causes mktime() 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 calen-

dar time, but with their values forced to the ranges indicated below. The ﬁnal value of

tm_mday is not set until tm_mon and tm_year are determined. mktime()

returns the speciﬁed calendar time encoded as a value of type time_t.

If the calendar time cannot be represented, the function returns the value (time_t)—

1 and sets errno to ERANGE. Note the value (time_t)—1 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 errno to reli-

ably detect an error condition.

tzset() Sets the values of the external variables timezone, daylight, and tzname according to

the contents of the

TZ environment variable (independent of any time value). The

functions localtime() , mktime(), ctime(), asctime(), and strftime()

(see strftime(3C)) call tzset() and use the values returned in the external variables

described below for their operations. tzset() can also be called directly by the user.

The <time.h> header ﬁle contains declarations of all relevant functions and externals. It also contains

the tm structure, which includes the following 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] */

HP-UX Release 11i: December 2000 − 2 − Section 3−−105

___