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Man page of NSR_GETDATE
NSR_GETDATE
Section: C Library Functions (3)
Updated: Dec 11, 08
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NAME
nsr_getdate - convert time and date from ASCII
SYNOPSIS
#include <sys/types.h>
time_t nsr_getdate(buf)
char *buf;
DESCRIPTION
The
nsr_getdate()
routine converts most common time specifications to standard UNIX
format. It takes a character string containing time and date as an
argumant and converts it to a time format.
The character string consists of zero or more specifications of the following
form:
- tod
-
A
tod
is a time of day, which is of the form
hh[:mm[:ss]]
(or
hhmm)
[meridian]
[zone].
If no meridian -
am
or
pm
- is specified, a 24-hour clock is used.
A
tod
may be specified as just
hh
followed by a
meridian.
If no zone (for example, GMT) is specified, the current timezone, as determined
by the second parameter,
now,
is assumed.
- date
-
A
date
is a specific month and day, and possibly a year.
The acceptable formats are
mm/dd[/yy]
and
monthname dd[, yy].
If omitted, the year defaults to the
current year.
If a year is specified
as a number in the range 70 and 99, 1900 is added.
If a year is in the range 00 and 30, 2000 is added.
The treatment of other years less than 100 is undefined.
If a number not followed by a day or relative time unit occurs, it will
be interpreted as a year if a
tod,
monthname,
and
dd
have already been specified; otherwise, it will be treated as a
tod.
This rule allows the output from
date(1)
or
ctime(3)
to be passed as input to
nsr_getdate.
- day
-
A
day
of the week may be specified; the current day will be used if appropriate.
A
day
may be preceded by a
number,
indicating which instance of that day is desired; the default is
1.
Negative
numbers
indicate times past. Some symbolic
numbers
are accepted:
last,
next,
and the ordinals
first
through
twelfth
(second
is ambiguous, and is not accepted as an ordinal number).
The symbolic number
next
is equivalent to
2;
thus,
next monday
refers not to the immediately coming Monday, but to the one a week later.
- relative time
-
Specifications relative to the current time are also accepted.
The format is
[number] unit;
acceptable units are
decade,
year,
quarter,
month,
fortnight,
week,
day,
hour,
minute,
and
second.
The actual date is formed as follows:
first, any absolute date and/or time
is processed and converted. Using that time as the base, day-of-week
specifications are added; last, relative specifications are used. If a
date or day is specified, and no absolute or relative time is given, midnight
is used.
Finally, a correction is applied so that the correct hour of the day is
produced after allowing for daylight savings time differences.
nsr_getdate
accepts most common abbreviations for days, months, and so forth; in particular,
it will recognize them with upper or lower case first letter, and will
recognize three-letter abbreviations for any of them, with or without
a trailing period. Units, such as
weeks,
may be specified in the singular or plural. Timezone and meridian
values may be in upper or lower case, and with or without periods.
SEE ALSO
ctime(3),
date(1),
ftime(3c),
localtime(2),
time(2)
BUGS
The grammar and scanner are rather primitive; certain desirable and
unambiguous constructions are not accepted. Worse yet, the meaning of
some legal phrases is not what is expected;
next week
is identical to
2 weeks.
The daylight savings time correction is not perfect, and can become incorrect
if provided times between midnight and 2:00 am on the days that the
time changes.
Because
localtime(2)
accepts an old-style time format without zone information,
passing
nsr_getdate
a current time containing a different zone will probably fail.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- SEE ALSO
-
- BUGS
-
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Time: 02:39:03 GMT, October 02, 2010