STRPTIME(3) manual page
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strptime - convert a string representation
of time to a time tm structure
#define _XOPEN_SOURCE /* See
feature_test_macros(7)
*/
#include <time.h>
char *strptime(const char *s, const char *format, struct
tm *tm);
The strptime() function is the converse of strftime(3)
;
it converts the character string pointed to by s to values which are stored
in the "broken-down time" structure pointed to by tm, using the format specified
by format.
The broken-down time structure tm is defined in <time.h> as follows:
struct tm {
int tm_sec; /* Seconds (0-60) */
int tm_min; /* Minutes (0-59) */
int tm_hour; /* Hours (0-23) */
int tm_mday; /* Day of the month (1-31) */
int tm_mon; /* Month (0-11) */
int tm_year; /* Year - 1900 */
int tm_wday; /* Day of the week (0-6, Sunday = 0) */
int tm_yday; /* Day in the year (0-365, 1 Jan = 0) */
int tm_isdst; /* Daylight saving time */
};
For more details on the tm structure, see ctime(3)
.
The format argument
is a character string that consists of field descriptors and text characters,
reminiscent of scanf(3)
. Each field descriptor consists of a % character
followed by another character that specifies the replacement for the field
descriptor. All other characters in the format string must have a matching
character in the input string, except for whitespace, which matches zero
or more whitespace characters in the input string. There should be whitespace
or other alphanumeric characters between any two field descriptors.
The
strptime() function processes the input string from left to right. Each
of the three possible input elements (whitespace, literal, or format) are
handled one after the other. If the input cannot be matched to the format
string, the function stops. The remainder of the format and input strings
are not processed.
The supported input field descriptors are listed below.
In case a text string (such as the name of a day of the week or a month
name) is to be matched, the comparison is case insensitive. In case a number
is to be matched, leading zeros are permitted but not required.
- %%
- The %
character.
- %a or %A
- The name of the day of the week according to the current
locale, in abbreviated form or the full name.
- %b or %B or %h
- The month name
according to the current locale, in abbreviated form or the full name.
- %c
- The date and time representation for the current locale.
- %C
- The century
number (0-99).
- %d or %e
- The day of month (1-31).
- %D
- Equivalent to %m/%d/%y.
(This is the American style date, very confusing to non-Americans, especially
since %d/%m/%y is widely used in Europe. The ISO 8601 standard format is
%Y-%m-%d.)
- %H
- The hour (0-23).
- %I
- The hour on a 12-hour clock (1-12).
- %j
- The day
number in the year (1-366).
- %m
- The month number (1-12).
- %M
- The minute (0-59).
- %n
- Arbitrary whitespace.
- %p
- The locale’s equivalent of AM or PM. (Note: there
may be none.)
- %r
- The 12-hour clock time (using the locale’s AM or PM). In the
POSIX locale equivalent to %I:%M:%S %p. If t_fmt_ampm is empty in the LC_TIME
part of the current locale, then the behavior is undefined.
- %R
- Equivalent
to %H:%M.
- %S
- The second (0-60; 60 may occur for leap seconds; earlier also
61 was allowed).
- %t
- Arbitrary whitespace.
- %T
- Equivalent to %H:%M:%S.
- %U
- The
week number with Sunday the first day of the week (0-53). The first Sunday
of January is the first day of week 1.
- %w
- The ordinal number of the day
of the week (0-6), with Sunday = 0.
- %W
- The week number with Monday the first
day of the week (0-53). The first Monday of January is the first day of week
1.
- %x
- The date, using the locale’s date format.
- %X
- The time, using the locale’s
time format.
- %y
- The year within century (0-99). When a century is not otherwise
specified, values in the range 69-99 refer to years in the twentieth century
(1969-1999); values in the range 00-68 refer to years in the twenty-first
century (2000-2068).
- %Y
- The year, including century (for example, 1991).
Some
field descriptors can be modified by the E or O modifier characters to
indicate that an alternative format or specification should be used. If
the alternative format or specification does not exist in the current locale,
the unmodified field descriptor is used.
The E modifier specifies that the
input string may contain alternative locale-dependent versions of the date
and time representation:
- %Ec
- The locale’s alternative date and time representation.
- %EC
- The name of the base year (period) in the locale’s alternative representation.
- %Ex
- The locale’s alternative date representation.
- %EX
- The locale’s alternative
time representation.
- %Ey
- The offset from %EC (year only) in the locale’s
alternative representation.
- %EY
- The full alternative year representation.
The O modifier specifies that the numerical input may be in an alternative
locale-dependent format:
- %Od or %Oe
- The day of the month using the locale’s
alternative numeric symbols; leading zeros are permitted but not required.
- %OH
- The hour (24-hour clock) using the locale’s alternative numeric symbols.
- %OI
- The hour (12-hour clock) using the locale’s alternative numeric symbols.
- %Om
- The month using the locale’s alternative numeric symbols.
- %OM
- The minutes
using the locale’s alternative numeric symbols.
- %OS
- The seconds using the
locale’s alternative numeric symbols.
- %OU
- The week number of the year (Sunday
as the first day of the week) using the locale’s alternative numeric symbols.
- %Ow
- The ordinal number of the day of the week (Sunday=0), using the locale’s
alternative numeric symbols.
- %OW
- The week number of the year (Monday as the first day of the week)
using the locale’s alternative numeric symbols.
- %Oy
- The year (offset from
%C) using the locale’s alternative numeric symbols.
The return
value of the function is a pointer to the first character not processed
in this function call. In case the input string contains more characters
than required by the format string, the return value points right after
the last consumed input character. In case the whole input string is consumed,
the return value points to the null byte at the end of the string. If strptime()
fails to match all of the format string and therefore an error occurred,
the function returns NULL.
SUSv2, POSIX.1-2001.
In principle,
this function does not initialize tm but stores only the values specified.
This means that tm should be initialized before the call. Details differ
a bit between different UNIX systems. The glibc implementation does not
touch those fields which are not explicitly specified, except that it recomputes
the tm_wday and tm_yday field if any of the year, month, or day elements
changed.
The aqyaq (year in century) specification is taken
to specify a year in the range 1950-2049 by glibc 2.0. It is taken to be
a year in 1969-2068 since glibc 2.1.
For reasons of symmetry,
glibc tries to support for strptime() the same format characters as for
strftime(3)
. (In most cases, the corresponding fields are parsed, but no
field in tm is changed.) This leads to
- %F
- Equivalent to %Y-%m-%d, the ISO
8601 date format.
- %g
- The year corresponding to the ISO week number, but
without the century (0-99).
- %G
- The year corresponding to the ISO week number.
(For example, 1991.)
- %u
- The day of the week as a decimal number (1-7, where
Monday = 1).
- %V
- The ISO 8601:1988 week number as a decimal number (1-53).
If the week (starting on Monday) containing 1 January has four or more
days in the new year, then it is considered week 1. Otherwise, it is the
last week of the previous year, and the next week is week 1.
- %z
- An RFC-822/ISO
8601 standard timezone specification.
- %Z
- The timezone name.
Similarly, because
of GNU extensions to strftime(3)
, %k is accepted as a synonym for %H, and
%l should be accepted as a synonym for %I, and %P is accepted as a synonym
for %p. Finally
- %s
- The number of seconds since the Epoch, 1970-01-01 00:00:00
+0000 (UTC). Leap seconds are not counted unless leap second support is
available.
The glibc implementation does not require whitespace between
two field descriptors.
The following example demonstrates the use
of strptime() and strftime(3)
.
#define _XOPEN_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
int
main(void)
{
struct tm tm;
char buf[255];
memset(&tm, 0, sizeof(struct tm));
strptime("2001-11-12 18:31:01", "%Y-%m-%d %H:%M:%S", &tm);
strftime(buf, sizeof(buf), "%d %b %Y %H:%M", &tm);
puts(buf);
exit(EXIT_SUCCESS);
}
time(2)
, getdate(3)
, scanf(3)
, setlocale(3)
, strftime(3)
This
page is part of release 3.78 of the Linux man-pages project. A description
of the project, information about reporting bugs, and the latest version
of this page, can be found at http://www.kernel.org/doc/man-pages/.
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