Tribblix: manual page: strptime.3c

STRPTIME(3C) Standard C Library Functions STRPTIME(3C)

NAME

strptime, strptime_l - date and time conversion

SYNOPSIS

#include <time.h>

char *strptime(const char *restrict buf,
const char *restrict format, struct tm *restrict tm);

#include <time.h>
#include <xlocale.h>

char *strptime_l(const char *restrict buf,
const char *restrict format, struct tm *restrict tm,
locale_t loc);

Non-zeroing Behavior
cc [flag...] file... -D_STRPTIME_DONTZERO [library...]
#include <time.h>

char *strptime(const char *restrict buf,
const char *restrict format, struct tm *restrict tm);

DESCRIPTION

The strptime() function converts the character string pointed to by
buf to values which are stored in the tm structure pointed to by tm,
using the format specified by format. The strptime_l() function is
identical to strptime() except instead of acting in the current
locale, it acts in the locale specified by the argument loc.

The format argument is composed of zero or more conversion
specifications. Each conversion specification is composed of a "%"
(percent) character followed by one or two conversion characters
which specify the replacement required. One or more white space
characters (as specified by isspace(3C)) may precede or follow a
conversion specification. There must be white-space or other non-
alphanumeric characters between any two conversion specifications.

A non-zeroing version of strptime(), described below under Non-
zeroing Behavior, is provided if _STRPTIME_DONTZERO is defined.

Conversion Specifications

The following conversion specifications are supported:

%%
Same as %.

%a
Day of week, using the locale's weekday names; either the
abbreviated or full name may be specified.

%A
Same as %a.

%b
Month, using the locale's month names; either the abbreviated
or full name may be specified.

%B
Same as %b.

%c
Locale's appropriate date and time representation.

%C
Century number (the year divided by 100 and truncated to an
integer as a decimal number [1,99]); single digits are preceded
by 0. If %C is used without the %y specifier, strptime()
assumes the year offset is zero in whichever century is
specified. Note the behavior of %C in the absence of %y is
not specified by any of the standards or specifications
described on the standards(7) manual page, so portable
applications should not depend on it. This behavior may change
in a future release.

%d
Day of month [1,31]; leading zero is permitted but not
required.

%D
Date as %m/%d/%y.

%e
Same as %d.

%h
Same as %b.

%H
Hour (24-hour clock) [0,23]; leading zero is permitted but not
required.

%I
Hour (12-hour clock) [1,12]; leading zero is permitted but not
required.

%j
Day number of the year [1,366]; leading zeros are permitted
but not required.

%m
Month number [1,12]; leading zero is permitted but not
required.

%M
Minute [0-59]; leading zero is permitted but not required.

%n
Any white space.

%p
Locale's equivalent of either a.m. or p.m.

%r
Appropriate time representation in the 12-hour clock format
with %p.

%R
Time as %H:%M.

SUSv3
%S
Seconds [0,60]; leading zero is permitted but not required. The
range of values is [00,60] rather than [00,59] to allow for the
occasional leap second.

Default and other standards

%S
Seconds [0,61]; leading zero is permitted but not required. The
range of values is [00,61] rather than [00,59] to allow for the
occasional leap second and even more occasional double leap
second.

%t
Any white space.

%T
Time as %H:%M:%S.

%U
Week number of the year as a decimal number [0,53], with Sunday
as the first day of the week; leading zero is permitted but not
required.

%w
Weekday as a decimal number [0,6], with 0 representing Sunday.

%W
Week number of the year as a decimal number [0,53], with Monday
as the first day of the week; leading zero is permitted but not
required.

%x
Locale's appropriate date representation.

%X
Locale's appropriate time representation.

%y
Year within century. When a century is not otherwise specified,
values in the range 69-99 refer to years in the twentieth
century (1969 to 1999 inclusive); values in the range 00-68
refer to years in the twenty-first century (2000 to 2068
inclusive).

%Y
Year, including the century (for example, 1993).

%Z
Time zone name or no characters if no time zone exists.

Modified Conversion Specifications

Some conversion specifications can be modified by the E and O
modifier characters to indicate that an alternate format or
specification should be used rather than the one normally used by the
unmodified specification. If the alternate format or specification
does not exist in the current locale, the behavior will be as if the
unmodified conversion specification were used.

%Ec
Locale's alternate appropriate date and time representation.

%EC
Name of the base year (era) in the locale's alternate
representation.

%Ex
Locale's alternate date representation.

%EX
Locale's alternate time representation.

%Ey
Offset from %EC (year only) in the locale's alternate
representation.

%EY
Full alternate year representation.

%Od
Day of the month using the locale's alternate numeric symbols.

%Oe
Same as %Od.

%OH
Hour (24-hour clock) using the locale's alternate numeric
symbols.

%OI
Hour (12-hour clock) using the locale's alternate numeric
symbols.

%Om
Month using the locale's alternate numeric symbols.

%OM
Minutes using the locale's alternate numeric symbols.

%OS
Seconds using the locale's alternate numeric symbols.

%OU
Week number of the year (Sunday as the first day of the week)
using the locale's alternate numeric symbols.

%Ow
Number of the weekday (Sunday=0) using the locale's alternate
numeric symbols.

%OW
Week number of the year (Monday as the first day of the week)
using the locale's alternate numeric symbols.

%Oy
Year (offset from %C) in the locale's alternate
representation and using the locale's alternate numeric
symbols.

General Specifications

A conversion specification that is an ordinary character is executed
by scanning the next character from the buffer. If the character
scanned from the buffer differs from the one comprising the
specification, the specification fails, and the differing and
subsequent characters remain unscanned.

A series of specifications composed of %n, %t, white-space characters
or any combination is executed by scanning up to the first character
that is not white space (which remains unscanned), or until no more
characters can be scanned. White space is defined by isspace(3C).

Any other conversion specification is executed by scanning characters
until a character matching the next specification is scanned, or
until no more characters can be scanned. These characters, except the
one matching the next specification, are then compared to the locale
values associated with the conversion specifier. If a match is
found, values for the appropriate tm structure members are set to
values corresponding to the locale information. If no match is found,
strptime() fails and no more characters are scanned.

The month names, weekday names, era names, and alternate numeric
symbols can consist of any combination of upper and lower case
letters. The user can request that the input date or time
specification be in a specific language by setting the LC_TIME
category using setlocale(3C).

Non-zeroing Behavior
In addition to the behavior described above by various standards, the
Solaris implementation of strptime() provides the following
extensions. These may change at any time in the future. Portable
applications should not depend on these extended features:

o If _STRPTIME_DONTZERO is not defined, the tm struct is
zeroed on entry and strptime() updates the fields of the
tm struct associated with the specifiers in the format
string.

o If _STRPTIME_DONTZERO is defined, strptime() does not zero
the tm struct on entry. Additionally, for some
specifiers, strptime() will use some values in the input
tm struct to recalculate the date and re-assign the
appropriate members of the tm struct.

The following describes extended features regardless of whether
_STRPTIME_DONTZERO is defined or not defined:

o If %j is specified, tm_yday is set; if year is given, and
if month and day are not given, strptime() calculates and
sets tm_mon, tm_mday, and tm_year.

o If %U or %W is specified and if weekday and year are given
and month and day of month are not given, strptime()
calculates and sets tm_mon, tm_mday, tm_wday, and tm_year.

The following describes extended features when _STRPTIME_DONTZERO is
not defined:

o If %C is specified and %y is not specified,
strptime()assumes 0 as the year offset, then calculates
the year, and assigns tm_year.

The following describes extended features when _STRPTIME_DONTZERO is
defined:

o If %C is specified and %y is not specified, strptime()
assumes the year offset of the year value of the tm_year
member of the input tm struct, then calculates the year
and assigns tm_year.

o If %j is specified and neither %y, %Y, nor %C are
specified, and neither month nor day of month are
specified, strptime() assumes the year value given by the
value of the tm_year field of the input tm struct. Then,
in addition to setting tm_yday, strptime() uses day-of-
year and year values to calculate the month and day-of-
month, and assigns tm_month and tm_mday.

o If %U or %W is specified, and if weekday and/or year are
not given, and month and day of month are not given,
strptime() will assume the weekday value and/or the year
value as the value of the tm_wday field and/or tm_year
field of the input tm struct. Then, strptime() will
calculate the month and day-of-month and assign tm_month,
tm_mday, and/or tm_year.

o If %p is specified and if hour is not specified,
strptime() will reference, and if needed, update the
tm_hour member. If the am_pm input is p.m. and the input
tm_hour value is between 0 - 11, strptime() will add 12
hours and update tm_hour. If the am_pm input is a.m. and
input tm_hour value is between 12 - 23, strptime() will
subtract 12 hours and update tm_hour.

RETURN VALUES

Upon successful completion, strptime() returns a pointer to the
character following the last character parsed. Otherwise, a null
pointer is returned.

USAGE

Several "same as" formats, and the special processing of white-space
characters are provided in order to ease the use of identical format
strings for strftime(3C) and strptime().

The strptime() function tries to calculate tm_year, tm_mon, and
tm_mday when given incomplete input. This allows the struct tm
created by strptime() to be passed to mktime(3C) to produce a time_t
value for dates and times that are representable by a time_t. As an
example, since mktime() ignores tm_yday, strptime() calculates tm_mon
and tm_mday as well as filling in tm_yday when %j is specified
without otherwise specifying a month and day within month.

ATTRIBUTES