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tzset |
Portability: | POSIX.1 conforming |
SYNOPSIS | |
DESCRIPTION | |
RETURN VALUE | |
CAUTION | |
EXAMPLE | |
RELATED FUNCTIONS | |
SEE ALSO |
SYNOPSIS |
#include <time.h> void tzset(void);
DESCRIPTION |
tzset
accesses the environment variable
TZ
, and
uses it to define time-zone information for the other timing functions (
ctime
,
localtime
,
strftime
, and
mktime
). If
TZ
is not defined, the
default time zone is implementation defined (see Timing Functions).
See
Timing Functions for the expected format of the
TZ
environment
variable.
In addition to saving time-zone information for the
other timing functions,
tzset
stores time-zone
names in the external array
tzname
, declared
in
<time.h>
as:
extern char *tzname[2];
tzname[0]
is set
by
tzset
to the name of the standard time
zone, and
tzname[1]
is set to the name
of the daylight savings time zone.
Note:
The
localtime
,
ctime
,
strftime
, and
mktime
functions
call
tzset
themselves during processing.
Therefore, you ordinarily do not have to call it yourself.
Note:
The prototype for
tzset
in
<time.h>
is not visible unless
_SASC_POSIX_SOURCE
or another POSIX feature test
macro is defined before
<time.h>
is
included.
RETURN VALUE |
There is no return value for
tzset
.
CAUTION |
The external variable
tzname
can be accessed only in the main load module of an application.
In other load modules, this information can be accessed by calling the function
_tzname()
.
EXAMPLE |
This example sets the
TZ
environment variable to Pacific Standard Time and Pacific Daylight
Time:
#include <stdlib.h> #include <time.h> #include <stdio.h> #define _SASC_POSIX_SOURCE1 main() { time_t timeval; setenv("TZ","PST8PDT"); tzset(); time(&timeval); /* Print the current Pacific time. */ printf("The current Pacific time and date are: %s", ctime(&timeval)); }
RELATED FUNCTIONS |
ctime
,
localtime
,
mktime
,
strftime
SEE ALSO |
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