strptime - convert a string representation of time to a
time tm structure
SYNOPSIS
#define _XOPEN_SOURCE /* glibc2 needs this */
#include <time.h>
char *strptime(const char *s, const char *format, struct
tm *tm);
DESCRIPTION
The strptime() function is the converse function to
strftime() and converts the character string pointed to by
s to values which are stored in the tm structure pointed
to by tm, using the format specified by format. Here for
mat is a character string that consists of field descrip
tors 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 whites
pace characters in the input string.
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 a weekday or month name) is
to be matched, the comparison is case insensitive. In
case a number is to be matched, leading zeros are permit
ted but not required.
%% The % character.
%a or %A
The weekday name 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).
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 or %t
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 behaviour is undefined.
%R Equivalent to %H:%M.
%S The second (0-60; 60 may occur for leap seconds;
earlier also 61 was allowed).
%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 weekday number (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
%Y The year, including century (for example, 1991).
Some field descriptors can be modified by the E or O modi
fier 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 representa
tion.
%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 alter
native numeric symbols.
%OI The hour (12-hour clock) using the locale's alter
native 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
%Ow The number of the weekday (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 alter
native numeric symbols.
The broken-down time structure tm is defined in <time.h>
as follows:
struct tm {
int tm_sec; /* seconds */
int tm_min; /* minutes */
int tm_hour; /* hours */
int tm_mday; /* day of the month */
int tm_mon; /* month */
int tm_year; /* year */
int tm_wday; /* day of the week */
int tm_yday; /* day in the year */
int tm_isdst; /* daylight saving time */
};
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 NUL 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.
CONFORMING TO
XPG4, SUSv2, Austin draft.
GNU EXTENSIONS
For reasons of symmetry, glibc tries to support for strp
time the same format characters as for strftime. (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.)
Monday = 1).
%V The ISO 8601:1988 week number as a decimal number
(1-53). If the week (starting on Monday) contain
ing 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 time zone specifica
tion.
%Z The timezone name.
Similarly, because of GNU extensions to strftime, %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, i.e., since
1970-01-01 00:00:00 UTC. Leap seconds are not
counted unless leap second support is available.
NOTES
In principle, this function does not initialize tm but
only stores the values specified. This means that tm
should be initialized before the call. Details differ a
bit between different Unix systems. The GNU libc imple
mentation 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.
This function is available since libc 4.6.8. Linux libc4
and libc5 includes define the prototype unconditionally;
glibc2 includes provide a prototype only when
_XOPEN_SOURCE or _GNU_SOURCE are defined.
Before libc 5.4.13 whitespace (and the 'n' and 't' speci
fications) was not handled, no 'E' and 'O' locale modifier
characters were accepted, and the 'C' specification was a
synonym for the 'c' specification.
The 'y' (year in century) specification is taken to spec
ify a year in the 20th century by libc4 and libc5. It is
taken to be 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.
SEE ALSO
time(2), scanf(3), setlocale(3), strftime(3)
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