GETDATE(3C) Standard C Library Functions GETDATE(3C)


NAME


getdate - convert user format date and time

SYNOPSIS


#include <time.h>

struct tm *getdate(const char *string);
extern int getdate_err;


DESCRIPTION


The getdate() function converts user-definable date and/or time
specifications pointed to by string to a tm structure. The tm structure
is defined in the <time.h> header.


User-supplied templates are used to parse and interpret the input string.
The templates are text files created by the user and identified via the
environment variable DATEMSK. Each line in the template represents an
acceptable date and/or time specification using conversion
specifications similar to those used by strftime(3C) and strptime(3C).
Dates before 1902 and after 2037 are illegal. The first line in the
template that matches the input specification is used for interpretation
and conversion into the internal time format.

Conversion Specifications


The following conversion specifications are supported:

%%
Same as %.


%a
Locale's abbreviated weekday name.


%A
Locale's full weekday name.


%b
Locale's abbreviated month name.


%B
Locale's full month name.


%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; see
standards(5). If used without the %y specifier, this format
specifier will assume the current year offset in whichever century
is specified. The only valid years are between 1902-2037.


%d
day of month [01,31]; leading zero is permitted but not required.


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


%e
Same as %d.


%h
Locale's abbreviated month name.


%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 alternative format or specification should
be used rather than the one normally used by the unmodified
specification. If the alternative format or specification does not exist
in the current locale, the behavior be as if the unmodified conversion
specification were used.

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


%EC
Name of the base year (period) in the locale's alternative
representation.


%Ex
Locale's alternative date representation.


%EX
Locale's alternative time representation.


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


%EY
Full alternative year representation.


%Od
Day of the month using the locale's alternative numeric symbols;
leading zeros are permitted but not required.


%Oe
Same as %Od.


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


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


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


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


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


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


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


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


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


Internal Format Conversion


The following rules are applied for converting the input specification
into the internal format:

o If only the weekday is given, today is assumed if the given
day is equal to the current day and next week if it is less.

o If only the month is given, the current month is assumed if
the given month is equal to the current month and next year if
it is less and no year is given. (The first day of month is
assumed if no day is given.)

o If only the year is given, the values of the tm_mon, tm_mday,
tm_yday, tm_wday, and tm_isdst members of the returned tm
structure are not specified.

o If the century is given, but the year within the century is
not given, the current year within the century is assumed.

o If no hour, minute, and second are given, the current hour,
minute, and second are assumed.

o If no date is given, today is assumed if the given hour is
greater than the current hour and tomorrow is assumed if it is
less.

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 conversion
specification, the specification fails, and the differing and subsequent
characters remain unscanned.


A series of conversion 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.


Any other conversion specification is executed by scanning characters
until a character matching the next conversion specification is scanned,
or until no more characters can be scanned. These characters, except the
one matching the next conversion 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, getdate()
fails and no more characters are scanned.


The month names, weekday names, era names, and alternative 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).

RETURN VALUES


If successful, getdate() returns a pointer to a tm structure; otherwise,
it returns NULL and sets the global variable getdate_err to indicate the
error. Subsequent calls to getdate() alter the contents of getdate_err.


The following is a complete list of the getdate_err settings and their
meanings:

1
The DATEMSK environment variable is null or undefined.


2
The template file cannot be opened for reading.


3
Failed to get file status information.


4
The template file is not a regular file.


5
An error is encountered while reading the template file.


6
The malloc() function failed (not enough memory is available).


7
There is no line in the template that matches the input.


8
The input specification is invalid (for example, February 31).


USAGE


The getdate() function makes explicit use of macros described on the
ctype(3C) manual page.

EXAMPLES


Example 1: Examples of the getdate() function.




The following example shows the possible contents of a template:


%m
%A %B %d %Y, %H:%M:%S
%A
%B
%m/%d/%y %I %p
%d,%m,%Y %H:%M
at %A the %dst of %B in %Y
run job at %I %p,%B %dnd
%A den %d. %B %Y %H.%M Uhr


The following are examples of valid input specifications for the above
template:


getdate("10/1/87 4 PM")
getdate("Friday")
getdate("Friday September 19 1987, 10:30:30")
getdate("24,9,1986 10:30")
getdate("at monday the 1st of december in 1986")
getdate("run job at 3 PM, december 2nd")


If the LANG environment variable is set to de (German), the following is
valid:


getdate("freitag den 10. oktober 1986 10.30 Uhr")


Local time and date specification are also supported. The following
examples show how local date and time specification can be defined in the
template.


+---------------------------+------------------+
|Invocation | Line in Template |
+---------------------------+------------------+
|getdate("11/27/86") | %m/%d/%y |
|getdate("27.11.86") | %d.%m.%y |
|getdate("86-11-27") | %y-%m-%d |
|getdate("Friday 12:00:00") | %A %H:%M:%S |
+---------------------------+------------------+


The following examples illustrate the Internal Format Conversion rules.
Assume that the current date is Mon Sep 22 12:19:47 EDT 1986 and the LANG
environment variable is not set.


+-------------+----------------+------------------------------+
|Input | Template Line | Date |
+-------------+----------------+------------------------------+
|Mon | %a | Mon Sep 22 12:19:48 EDT 1986 |
|Sun | %a | Sun Sep 28 12:19:49 EDT 1986 |
|Fri | %a | Fri Sep 26 12:19:49 EDT 1986 |
|September | %B | Mon Sep 1 12:19:49 EDT 1986 |
|January | %B | Thu Jan 1 12:19:49 EST 1987 |
|December | %B | Mon Dec 1 12:19:49 EDT 1986 |
|Sep Mon | %b %a | Mon Sep 1 12:19:50 EDT 1986 |
|Jan Fri | %b %a | Fri Jan 2 12:19:50 EST 1987 |
|Dec Mon | %b %a | Mon Dec 1 12:19:50 EST 1986 |
|Jan Wed 1989 | %b %a %Y | Wed Jan 4 12:19:51 EST 1989 |
|Fri 9 | %a %H | Fri Sep 26 09:00:00 EDT 1986 |
|Feb 10:30 | %b %H:%S | Sun Feb 1 10:00:30 EST 1987 |
|10:30 | %H:%M | Tue Sep 23 10:30:00 EDT 1986 |
|13:30 | %H:%M | Mon Sep 22 13:30:00 EDT 1986 |
+-------------+----------------+------------------------------+

ATTRIBUTES


See attributes(5) for descriptions of the following attributes:


+--------------------+-----------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|CSI | Enabled |
+--------------------+-----------------+
|Interface Stability | Standard |
+--------------------+-----------------+
|MT-Level | MT-Safe |
+--------------------+-----------------+

SEE ALSO


ctype(3C), mktime(3C), setlocale(3C), strftime(3C), strptime(3C),
attributes(5), environ(5), standards(5)


November 1, 2003 GETDATE(3C)