getdate, getdate_r - convert a date-plus-time string to broken-down time
Standard C library (
libc,
-lc)
#include <time.h>
struct tm *getdate(const char *string);
extern int getdate_err;
int getdate_r(const char *restrict string, struct tm *restrict res);
getdate():
_XOPEN_SOURCE >= 500
getdate_r():
_GNU_SOURCE
The function
getdate() converts a string representation of a date and
time, contained in the buffer pointed to by
string, into a broken-down
time. The broken-down time is stored in a
tm structure, and a pointer
to this structure is returned as the function result. This
tm structure
is allocated in static storage, and consequently it will be overwritten by
further calls to
getdate().
In contrast to
strptime(3), (which has a
format argument),
getdate() uses the formats found in the file whose full pathname is
given in the environment variable
DATEMSK. The first line in the file
that matches the given input string is used for the conversion.
The matching is done case insensitively. Superfluous whitespace, either in the
pattern or in the string to be converted, is ignored.
The conversion specifications that a pattern can contain are those given for
strptime(3). One more conversion specification is specified in
POSIX.1-2001:
- %Z
- Timezone name. This is not implemented in glibc.
When
%Z is given, the structure containing the broken-down time is
initialized with values corresponding to the current time in the given
timezone. Otherwise, the structure is initialized to the broken-down time
corresponding to the current local time (as by a call to
localtime(3)).
When only the day of the week is given, the day is taken to be the first such
day on or after today.
When only the month is given (and no year), the month is taken to be the first
such month equal to or after the current month. If no day is given, it is the
first day of the month.
When no hour, minute, and second are given, the current hour, minute, and second
are taken.
If no date is given, but we know the hour, then that hour is taken to be the
first such hour equal to or after the current hour.
getdate_r() is a GNU extension that provides a reentrant version of
getdate(). Rather than using a global variable to report errors and a
static buffer to return the broken down time, it returns errors via the
function result value, and returns the resulting broken-down time in the
caller-allocated buffer pointed to by the argument
res.
When successful,
getdate() returns a pointer to a
struct tm.
Otherwise, it returns NULL and sets the global variable
getdate_err to
one of the error numbers shown below. Changes to
errno are unspecified.
On success
getdate_r() returns 0; on error it returns one of the error
numbers shown below.
The following errors are returned via
getdate_err (for
getdate())
or as the function result (for
getdate_r()):
- 1
- The DATEMSK environment variable is not defined, or
its value is an empty string.
- 2
- The template file specified by DATEMSK cannot be
opened for reading.
- 3
- Failed to get file status information.
- 4
- The template file is not a regular file.
- 5
- An error was encountered while reading the template
file.
- 6
- Memory allocation failed (not enough memory
available).
- 7
- There is no line in the file that matches the input.
- 8
- Invalid input specification.
- DATEMSK
- File containing format patterns.
-
TZ, LC_TIME
- Variables used by strptime(3).
For an explanation of the terms used in this section, see
attributes(7).
Interface |
Attribute |
Value |
getdate () |
Thread safety |
MT-Unsafe race:getdate env locale |
getdate_r () |
Thread safety |
MT-Safe env locale |
POSIX.1-2001, POSIX.1-2008.
The POSIX.1 specification for
strptime(3) contains conversion
specifications using the
%E or
%O modifier, while such
specifications are not given for
getdate(). In glibc,
getdate()
is implemented using
strptime(3), so that precisely the same
conversions are supported by both.
The program below calls
getdate() for each of its command-line arguments,
and for each call displays the values in the fields of the returned
tm
structure. The following shell session demonstrates the operation of the
program:
$ TFILE=$PWD/tfile
$ echo '%A' > $TFILE # Full name of the day of the week
$ echo '%T' >> $TFILE # Time (HH:MM:SS)
$ echo '%F' >> $TFILE # ISO date (YYYY-MM-DD)
$ date
$ export DATEMSK=$TFILE
$ ./a.out Tuesday '2009-12-28' '12:22:33'
Sun Sep 7 06:03:36 CEST 2008
Call 1 ("Tuesday") succeeded:
tm_sec = 36
tm_min = 3
tm_hour = 6
tm_mday = 9
tm_mon = 8
tm_year = 108
tm_wday = 2
tm_yday = 252
tm_isdst = 1
Call 2 ("2009-12-28") succeeded:
tm_sec = 36
tm_min = 3
tm_hour = 6
tm_mday = 28
tm_mon = 11
tm_year = 109
tm_wday = 1
tm_yday = 361
tm_isdst = 0
Call 3 ("12:22:33") succeeded:
tm_sec = 33
tm_min = 22
tm_hour = 12
tm_mday = 7
tm_mon = 8
tm_year = 108
tm_wday = 0
tm_yday = 250
tm_isdst = 1
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
int
main(int argc, char *argv[])
{
struct tm *tmp;
for (size_t j = 1; j < argc; j++) {
tmp = getdate(argv[j]);
if (tmp == NULL) {
printf("Call %zu failed; getdate_err = %d\n",
j, getdate_err);
continue;
}
printf("Call %zu (\"%s\") succeeded:\n", j, argv[j]);
printf(" tm_sec = %d\n", tmp->tm_sec);
printf(" tm_min = %d\n", tmp->tm_min);
printf(" tm_hour = %d\n", tmp->tm_hour);
printf(" tm_mday = %d\n", tmp->tm_mday);
printf(" tm_mon = %d\n", tmp->tm_mon);
printf(" tm_year = %d\n", tmp->tm_year);
printf(" tm_wday = %d\n", tmp->tm_wday);
printf(" tm_yday = %d\n", tmp->tm_yday);
printf(" tm_isdst = %d\n", tmp->tm_isdst);
}
exit(EXIT_SUCCESS);
}
time(2),
localtime(3),
setlocale(3),
strftime(3),
strptime(3)