STRPTIME(3) Linux Programmer's Manual STRPTIME(3)
NAME
strptime - convert a string representation of time to a time tm struc-
ture
SYNOPSIS
#define_XOPEN_SOURCE /* glibc2 needs this */
#include<time.h>
char*strptime(constchar*s,constchar*format,structtm*tm);
DESCRIPTION
The strptime() function is the converse function to strftime() and con-
verts 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 format 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 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
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 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 a weekday or month name) is to be matched, the compari-
son is case insensitive. In case a number is to be matched, leading
zeros are permitted 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).
%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 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 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 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 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 charac-
ters 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 number of the weekday (Sunday=0) using the locale's alterna-
tive 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 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 */
};
RETURNVALUE
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 for-
mat string and therefore an error occurred the function returns NULL.
CONFORMINGTO
XPG4, SUSv2, POSIX 1003.1-2001.
EXAMPLE
The following example demonstrates the use of strptime() and strf-
time().
#include <stdio.h>
#include <time.h>
int main() {
struct tm tm;
char buf[255];
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);
return 0;
}
GNUEXTENSIONS
For reasons of symmetry, glibc tries to support for strptime 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.)
%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. Other-
wise, 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 specification.
%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.
The GNU libc implementation does not require whitespace between two
field descriptors.
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 implementation does not touch those fields which are not explic-
itly 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' specifications) 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 specify 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.
SEEALSO
time(2), getdate(3), scanf(3), setlocale(3), strftime(3)
GNU 2001-11-12 STRPTIME(3)
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