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Linux 2.6 - man page for strptime (linux section 3)

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

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

SYNOPSIS
       #define _XOPEN_SOURCE	   /* See feature_test_macros(7) */
       #include <time.h>

       char *strptime(const char *s, const char *format, struct tm *tm);

DESCRIPTION
       The strptime() function is the converse function to strftime(3) 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 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 characters in the format  string  must	have  a  matching
       character  in  the  input string, except for whitespace, which matches zero or more white-
       space 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	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 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 stan-
	      dard 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  equiva-
	      lent  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 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 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 spec-
       ification 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-depen-
       dent 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 number of the weekday (Sunday=0) using the locale's  alternative  numeric  sym-
	      bols.

       %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 */
	   };

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.

CONFORMING TO
       SUSv2, POSIX.1-2001.

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.

       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.

   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 con-
	      sidered  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  sec-
	      onds are not counted unless leap second support is available.

       The glibc implementation does not require whitespace between two field descriptors.

EXAMPLE
       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);
       }

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

COLOPHON
       This  page  is  part of release 3.55 of the Linux man-pages project.  A description of the
       project,    and	  information	 about	  reporting    bugs,	can    be    found     at
       http://www.kernel.org/doc/man-pages/.

GNU					    2009-12-05				      STRPTIME(3)


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