© 2005-2007 Nokia
#include <time.h>
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void
tzset (void); |
If TZ does not appear in the environment, the best available approximation to local wall clock time, is used.
If TZ appears in the environment but its value is a null string, Coordinated Universal Time (UTC) is used (without leap second correction).
#include <time.h>
#include <stdio.h>
int main(){
time_t t;
char* c_time;
tzset(); //Call tzset
c_time = ctime (&t); //Get time-string using ctime for Epoc time
printf ("Time from ctime after tzset: %s", c_time);
return 0;
}
Output
Time from ctime after tzset: Sun Apr 7 02:24:08 1974
std offset
[
dst
[offset]
[,rule]
]
Where:
| std and dst | Three or more bytes that are the designation for the standard (std) or summer (dst) time zone. Only std is required; if dst is missing, then summer time does not apply in this locale. Upper and lowercase letters are explicitly allowed. Any characters except a leading colon (‘:’), digits, comma (‘,’), minus (‘-’), plus (‘+’), and ASCII NUL are allowed. |
| offset |
Indicates the value one must add to the local time to arrive at
Coordinated Universal Time.
The
offset
has the form:
hh[
: mm
[:ss]
]
The minutes (mm) and seconds (ss) are optional. The hour (hh) is required and may be a single digit. The offset following std is required. If no offset follows dst, summer time is assumed to be one hour ahead of standard time. One or more digits may be used; the value is always interpreted as a decimal number. The hour must be between zero and 24, and the minutes (and seconds) — if present — between zero and 59. If preceded by a (‘-’) the time zone shall be east of the Prime Meridian; otherwise it shall be west (which may be indicated by an optional preceding (‘+’)). |
| rule |
Indicates when to change to and back from summer time.
The
rule
has the form:
date/time,date/time
where the first date describes when the change from standard to summer time occurs and the second date describes when the change back happens. Each time field describes when, in current local time, the change to the other time is made. The format of date is one of the following: |
| J n | The Julian day n (1 <= n <= 365). Leap days are not counted; that is, in all years — including leap years — February 28 is day 59 and March 1 is day 60. It is impossible to explicitly refer to the occasional February 29. |
| n | The zero-based Julian day (0 <= n <= 365 ) . Leap days are counted, and it is possible to refer to February 29. |
| M m.n.d |
The
d ’th
day (0 <=
d
<= 6)
of week
n
of month
m
of the year
(1 <=
n
<= 5),
(1 <=
m
<= 12),
where week 5 means
"
the last
d
day in month
m
"
which may occur in either the fourth or the fifth week).
Week 1 is the
first week in which the
d ’th
day occurs.
Day zero is Sunday.
The time has the same format as offset except that no leading sign (‘-’) or (‘+’) is allowed. The default, if time is not given, is 02:00:00. |
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© 2005-2007 Nokia |
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