strptime(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ATTRIBUTES | CONFORMING TO | NOTES | EXAMPLES | SEE ALSO | COLOPHON

STRPTIME(3)             Linux Programmer's Manual            STRPTIME(3)

NAME         top

       strptime - convert a string representation of time to a time tm
       structure

SYNOPSIS         top

       #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         top

       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.

RETURN VALUE         top

       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         top

       For an explanation of the terms used in this section, see
       attributes(7).

       ┌───────────────────────────┬───────────────┬────────────────────┐
       │Interface                  Attribute     Value              │
       ├───────────────────────────┼───────────────┼────────────────────┤
       │strptime()                 │ Thread safety │ MT-Safe env locale │
       └───────────────────────────┴───────────────┴────────────────────┘

CONFORMING TO         top

       POSIX.1-2001, POSIX.1-2008, SUSv2.

NOTES         top

       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         top

       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(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         top

       time(2), getdate(3), scanf(3), setlocale(3), strftime(3)

COLOPHON         top

       This page is part of release 5.12 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
       https://www.kernel.org/doc/man-pages/.

GNU                            2021-03-22                    STRPTIME(3)

Pages that refer to this page: dpkg-parsechangelog(1)ctime(3)getdate(3)strftime(3)locale(5)locale(7)time(7)