strptime(3) Library Functions Manual strptime(3)
NAME
strptime - convert a string representation of time to a time tm struc-
ture
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#define _XOPEN_SOURCE /* See feature_test_macros(7) */
#include <time.h>
char *strptime(const char *restrict s, const char *restrict format,
struct tm *restrict tm);
DESCRIPTION
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 "bro-
ken-down time" structure pointed to by tm, using the format specified by
format.
The broken-down time structure tm is described in tm(3type).
The format argument is a character string that consists of field de-
scriptors and text characters, reminiscent of scanf(3). Each field de-
scriptor consists of a % character followed by another character that
specifies the replacement for the field descriptor. All other charac-
ters 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 al-
phanumeric 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 for-
mat) 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 twen-
tieth 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 rep-
resentation.
%EY The full alternative year representation.
The O modifier specifies that the numerical input may be in an alterna-
tive locale-dependent format:
%Od or %Oe
The day of the month using the locale's alternative numeric sym-
bols; 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.
RETURN VALUE
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.
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
┌─────────────────────────────────┬───────────────┬────────────────────┐
│ Interface │ Attribute │ Value │
├─────────────────────────────────┼───────────────┼────────────────────┤
│ strptime() │ Thread safety │ MT-Safe env locale │
└─────────────────────────────────┴───────────────┴────────────────────┘
STANDARDS
POSIX.1-2008.
HISTORY
POSIX.1-2001, SUSv2.
NOTES
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 'y' (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.
glibc notes
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.
EXAMPLES
The following example demonstrates the use of strptime() and strf-
time(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(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);
}
SEE ALSO
time(2), getdate(3), scanf(3), setlocale(3), strftime(3)
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