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Date Time Input/Output

Format Flags
Date Facet
Date Input Facet
Time Facet
Time Input Facet
Date Time Formatter/Parser Objects
Date Time IO Tutorial

Date Time IO System

Exception Handling on Streams

As of version 1.33, the date_time library utilizes a new IO streaming system. This new system gives the user great control over how dates and times can be represented. The customization options can be broken down into two groups: format flags and string elements. Format flags provide flexibility in the order of the date elements as well as the type. Customizing the string elements allows the replacement of built in strings from month names, weekday names, and other strings used in the IO.

The output system is based on a date_facet (derived from std::facet), while the input system is based on a date_input_facet (also derived from std::facet). The time and local_time facets are derived from these base types. The output system utilizes three formatter objects, whereas the input system uses four parser objects. These formatter and parser objetcs are also customizable.

It is important to note, that while all the examples shown here use narrow streams, there are wide stream facets available as well (see IO Objects for a complete list).

It should be further noted that not all compilers are capable of using this IO system. For those compilers the IO system used in previous date_time versions is still available. The "legacy IO" is automatically selected for these compilers, however, the legacy IO system can be manually selected by defining USE_DATE_TIME_PRE_1_33_FACET_IO. See the Build-Compiler Information for more information.

Exception Handling on Streams

When an error occurs during the input streaming process, the std::ios_base::failbit will (always) be set on the stream. It is also possible to have exceptions thrown when an error occurs. To "turn on" these exceptions, call the stream's exceptions function with a parameter of std::ios_base::failbit.

// "Turning on" exceptions
date d(not_a_date_time);
std::stringstream ss;
ss.exceptions(std::ios_base::failbit);
ss.str("204-Jan-01");
ss >> d; // throws bad_year exception AND sets failbit on stream
A simple example of this new system:
//example to customize output to be "LongWeekday LongMonthname day, year"
//                                  "%A %b %d, %Y"
date d(2005,Jun,25);
date_facet* facet(new date_facet("%A %B %d, %Y"));
std::cout.imbue(std::locale(std::cout.getloc(), facet));
std::cout << d << std::endl;
// "Saturday June 25, 2005"

Format Flags

Many of the format flags this new system uses for output are those used by strftime(...), but not all. Some new flags have been added, and others overridden. The input system supports only specific flags, therefore, not all flags that work for output will work with input (we are currently working to correct this situation).

The following tables list the all the flags available for both date_time IO as well as strftime. Format flags marked with a single asterisk (*) have a behavior unique to date_time. Those flags marked with an exclamation point (!) are not usable for input (at this time). The first table is for dates, and the second table is for times.

Date Facet Format Flags

Format Specifier Description
Example
 
%a
 Abbreviated weekday name 
"Mon" => Monday
%A
 Long weekday name 
"Monday"
%b
 Abbreviated month name 
"Feb" => February
%B
 Full month name 
"February"
%c !
 The preferred date and time representation for the current locale. 




%C !

The century number (year/100) as a 2-digit integer.







%d

Day of the month as decimal 01 to 31







%D !

Equivalent to %m/%d/%y







%e

Like %d, the day of the month as a decimal number, but a leading zero is replaced by a space







%G !

This has the same format and value as %y, except that if the ISO week number belongs to the previous or next year, that year is used instead.







%g !

Like %G, but without century.







%h !

 Equivalent to %b







%j

Day of year as decimal from 001 to 366 for leap years, 001 - 365 for non-leap years.



"060" => Feb-29




%m

Month name as a decimal 01 to 12



"01" => January




%u !

The  day of the week as a decimal, range 1 to 7, Monday being 1.







%U

The week number of the current year as a decimal number, range 00 to 53, starting with the first Sunday as the first day of week 01. In 2005, Jan 1st falls on a Saturday, so therefore it falls within week 00 of 2005 (week 00 spans 2004-Dec-26 to 2005-Jan-01. This also happens to be week 53 of 2004).



date d(2005, Jan, 1); // Saturday
  // with format %U
  ss << d; // "00"
  d += day(1); // Sunday
  ss << d; // "01" beginning of week 1




%V !

The ISO 8601:1988 week number of the current year as  a  decimal number,  range 01 to 53, where week 1 is the first week that has at least 4 days in the current year,  and  with  Monday  as  the first day of the week.







%w

Weekday as decimal number 0 to 6



"0" => Sunday




%W

Week number 00 to 53 where Monday is first day of week 1



date d(2005, Jan, 2); // Sunday
  // with format %W
  ss << d; // "00"
  d += day(1); // Monday
  ss << d; // "01" beginning of week 1




%x

Implementation defined date format from the locale.



date d(2005,Oct,31);
  date_facet* f = new date_facet("%x");
   
  locale loc = locale(locale("en_US"), f);
  cout.imbue(loc);
  cout << d; // "10/31/2005"
    
  loc = locale(locale("de_DE"), f);
  cout.imbue(loc);
  cout << d; // "31.10.2005"




%y

Two digit year



"05" => 2005




%Y

Four digit year



"2005"




%Y-%b-%d

Default date format



"2005-Apr-01"




%Y%m%d

ISO format



"20050401"




%Y-%m-%d

ISO extended format



"2005-04-01"








    
    Time Facet Format Flags
    










Format Specifier
Description



Example






%- *!

Placeholder for the sign of a duration. Only displays when the duration is negative.



"-13:15:16"




%+ *!

Placeholder for the sign of a duration. Always displays for both positive and negative.



"+13:15:16"




%f

Fractional seconds are always used, even when their value is zero



"13:15:16.000000"




%F *

Fractional seconds are used only when their value is not zero.



"13:15:16"
  "05:04:03.001234"
            




%I !

The hour as a decimal number using a 12-hour clock



 




%k !

The hour (24-hour clock) as a decimal number (range 0 to 23); single digits are preceded by a blank.







%l !

The hour (12-hour clock) as a decimal number (range  1  to  12); single digits are preceded by a blank.







%p !

Either `AM' or `PM' according to the given time value, or the corresponding strings for the current locale.







%P !

Like %p but in lowercase: `am' or `pm' or a corresponding string for the current locale.







%r !

The time in a.m. or p.m. notation. In the POSIX locale this is equivalent to `%I:%M:%S %p'







%R !

The time in 24-hour notation (%H:%M)







%s *

Seconds with fractional seconds.



"59.000000"




%S

Seconds only



"59"




%T !

The time in 24-hour notation (%H:%M:%S)







%q

ISO time zone (output only). This flag is ignored when using the time_facet with a ptime.



"-0700" // Mountain Standard Time




%Q

ISO extended time zone (output only). This flag is ignored when using the time_facet with a ptime.



"-05:00" // Eastern Standard Time




%z *!

Abbreviated time zone (output only). This flag is ignored when using the time_facet with a ptime.



"MST" // Mountain Standard Time




%Z *!

Full time zone name (output only). This flag is ignored when using the time_facet with a ptime.



"EDT" // Eastern Daylight Time




%ZP *

Posix time zone string (available to both input and output). This flag is ignored when using the time_facet with a ptime. For complete details on posix time zone strings, see posix_time_zone class.



"EST-05EDT+01,M4.1.0/02:00,M10.5.0/02:00"




%x %X

Implementation defined date/time format from the locale.



date d(2005,Oct,31);
  ptime pt(d, hours(20));
  time_facet* f = new time_facet("%x %X");
   
  locale loc = locale(locale("en_US"), f);
  cout.imbue(loc);
  cout << pt; // "10/31/2005 08:00:00 PM"
    
  loc = locale(locale("de_DE"), f);
  cout.imbue(loc);
  cout << pt; // "31.10.2005 20:00:00"




%Y%m%dT%H%M%S%F%q

ISO format



"20051015T131211-0700"
  // Oct 15, 2005 13:12:11 MST
            




%Y-%m-%d %H:%M:%S%F%Q

Extended ISO format



"2005-10-15 13:12:11-07:00"




%Y-%b-%d %H:%M:%S%F %z

Default format used when outputting ptime and local_date_time.



"2005-Oct-15 13:12:11 MST"




%Y-%b-%d %H:%M:%S%F %ZP

Default format used when inputting ptime and local_date_time.



"2005-Oct-15 13:12:11 MST-07"




%-%H:%M:%S%F !

Default time_duration format for output. Sign will only be displayed for negative durations.



"-13:14:15.003400"




%H:%M:%S%F

Default time_duration format for input.



"13:14:15.003400"






  


* Signifies flags that have a behavior unique to date_time.


! Signifies flags that currently do not work for input.




The following table lists the available facets.



IO Objects



    









Output
Input





date_facet
date_input_facet




wdate_facet
wdate_input_facet




time_facet
time_input_facet




wtime_facet
wtime_input_facet





local_time_facet*

local_time_input_facet*





wlocal_time_facet*

wlocal_time_input_facet*







    * These links lead to the time_facet and time_input_facet reference sections. They are not actual classes but typedefs.
  



Formatter/Parser Objects


To implement the new i/o facets the date-time library uses a number of new parsers and formatters. These classes are available for users that want to implement specialized input/output routines.



    









Output
Input





period_formatter
period_parser




date_generator_formatter
date_generator_parser




special_values_formatter
special_values_parser




 
format_date_parser







  





Date Facet

Introduction -
  Construction -
  Accessors

Introduction


The boost::date_time::date_facet enables users to have significant control over the output streaming of dates (and other gregorian objects). The date_facet is typedef'd in the gregorian namespace as date_facet and wdate_facet. 
  



Construction



    









Syntax
Description






date_facet()

Default constructor





date_facet(...)
  Parameters:
    char_type* format
    input_collection_type

Format given will be used for date output. All other formats will use their defaults. Collection is the set of short names to be used for months. All other name collections will use their defaults.





date_facet(...)
  Parameters:
    char_type* format
    period_formatter_type
    special_values_formatter_type
    date_gen_formatter_type

Format given will be used for date output. The remaining parameters are formatter objects. Further details on these objects can be found here. This constructor also provides default arguments for all parameters except the format. Therefore, date_facet("%m %d %Y") will work.







  



Accessors



    










Syntax
Description



Example






void format(char_type*)

Set the format for dates.



date_facet* f = new date_facet();
f->format("%m %d %Y");




void set_iso_format()

Sets the date format to ISO



f->set_iso_format();
// "%Y%m%d"




void set_iso_extended_format()

Sets the date format to ISO Extended



f->set_iso_extended_format();
// "%Y-%m-%d"




void month_format(char_type*)

Set the format for months when they are 'put' individually.



f->month_format("%B"); 
ss << greg_month(12); // "December"




void weekday_format(char_type*)

Set the format for weekdays when they are 'put' individually.



f->weekday_format("%a");
ss << greg_weekday(2); // "Tue"




void period_formatter(...)
  Parameter:
    period_formatter_type

Replaces the period formatter object with a user created one.



see the tutorial for a complete example.




void special_values_formatter(...)
  Parameter:
    special_values_formatter_type

Replaces the special_values formatter object with a user created one.



see the tutorial for a complete example.




void date_gen_phrase_strings(...)
  Parameters:
    input_collection_type
    date_gen_formatter_type::
      phrase_elements

Sets new date generator phrase strings in date_gen_formatter. The input collection is a vector of strings (for details on these strings see date generator formatter/parser documentation). The phrase_elements parameter is an enum, defined in the date_generator_formatter object, that has a default value of 'first'. It is used to indicate what the position of the first string in the collection will be.







void short_weekday_names(...)
  Parameter:
    input_collection_type

Replace strings used when 'putting' short weekdays.



see the tutorial for a complete example.




void long_weekday_names(...)
  Parameter:
    input_collection_type

Replace strings used when 'putting' long weekdays.



see the tutorial for a complete example.




void short_month_names(...)
  Parameter:
    input_collection_type

Replace strings used when 'putting' short months.



see the tutorial for a complete example.




void long_month_names(...)
  Parameter:
    input_collection_type

Replace strings used when 'putting' long months.



see the tutorial for a complete example.




OutItrT put(...)
  Common parameters for all 
  'put' functions:
    OutItrT 
    ios_base
    char_type
  Unique parameter for 'put' funcs:
    gregorian object

There are 12 put functions in the date_facet. The common paraeters are: an iterator pointing to the next item in the stream, an ios_base object, and the fill character. Each unique gregorian object has it's own put function. Each unique put function is described below.







OutItrT put(..., date)

Puts a date object into the stream using the format set by format(...) or the default.







OutItrT put(..., days)

Puts a days object into the stream as a number.







OutItrT put(..., month)

Puts a month object into the stream using the format set by month_format(...) or the default.







OutItrT put(..., day)

Puts a day of month object into the stream as a two digit number.



"01" // January 1st




OutItrT put(..., day_of_week)

Puts a day of week object into the stream using the format set by weekday_format(...) or the default.







OutItrT put(..., date_period)

Puts a date_period into the stream. The format of the dates will use the format set by format(..) or the default date format. The type of period (open or closed range) and the delimiters used are those used by the period_formatter.







OutItrT put(..., partial_date)

Puts a partial_date date_generator object into the stream. The month format used is set by month_format(..) or the default. The day of month is represented as a two digit number.



"01 Jan" // default formats
"01 January" // long month format




OutItrT put(..., date_generator)
  Date Generator Type:
    nth_day_of_the_week_in_month

Puts a nth_day_of_the_week_in_month object into the stream. The month format is set by month_format(...) or the default. The weekday format is set by weekday_format(...) or the default. The remaining phrase elements are set in the date_generator_formatter.



"third Fri in May" // defaults




OutItrT put(..., date_generator)
  Date Generator Type:
    first_day_of_the_week_in_month

Puts a first_day_of_the_week_in_month object into the stream. The month format is set by month_format(...) or the default. The weekday format is set by weekday_format(...) or the default. The remaining phrase elements are set in the date_generator_formatter.



"first Wed of Jun" // defaults




OutItrT put(..., date_generator)
  Date Generator Type:
    last_day_of_the_week_in_month

Puts a last_day_of_the_week_in_month object into the stream. The month format is set by month_format(...) or the default. The weekday format is set by weekday_format(...) or the default. The remaining phrase elements are set in the date_generator_formatter.



"last Tue of Mar" // defaults




OutItrT put(..., date_generator)
  Date Generator Type:
    first_day_of_the_week_after

Puts a first_day_of_the_week_after object into the stream. The weekday format is set by weekday_format(...) or the default. The remaining phrase elements are set in the date_generator_formatter.



"first Sat after" // defaults




OutItrT put(..., date_generator)
  Date Generator Type:
    first_day_of_the_week_before

Puts a first_day_of_the_week_before object into the stream. The weekday format is set by weekday_format(...) or the default. The remaining phrase elements are set in the date_generator_formatter.



"first Mon before" // defaults






  







Date Input Facet

Introduction -
  Construction -
  Accessors

Introduction


The boost::date_time::date_input_facet enables users to have significant control how dates (and other gregorian objects) are streamed in. The date_input_facet is typedef'd in the gregorian namespace as date_input_facet and wdate_input_facet. 
  



Construction



    









Syntax
Description






date_input_facet()

Default constructor





date_input_facet(string_type format)

Format given will be used for date input. All other formats will use their defaults.





date_input_facet(...)
  Parameters:
    string_type format
    format_date_parser_type
    special_values_parser_type
    period_parser_type
    date_gen_parser_type

Format given will be used for date input. The remaining parameters are parser objects. Further details on these objects can be found here.







  



Accessors



    










Syntax
Description



Example






void format(char_type*)

Set the format for dates.



date_input_facet* f = 
    new date_input_facet();
f->format("%m %d %Y");




void set_iso_format()

Sets the date format to ISO



f->set_iso_format();
// "%Y%m%d"




void set_iso_extended_format()

Sets the date format to ISO Extended



f->set_iso_extended_format();
// "%Y-%m-%d"




void month_format(char_type*)

Set the format when 'get'ing months individually.



f->month_format("%B");
ss.str("March");
ss >> m; // March




void weekday_format(char_type*)

Set the format when 'get'ing weekdays individually.



f->weekday_format("%a");
ss.str("Sun");
ss >> wd; // Sunday




void year_format(char_type*)

Set the format when 'get'ing years individually.



f->weekday_format("%y");
ss.str("04");
ss >> year; // 2004




void period_parser(...)
  Parameter:
    period_parser_type

Replaces the period parser object with a user created one.



see the tutorial for a complete example.




void special_values_parser(...)
  Parameter:
    special_values_parser_type

Replaces the special_values parser object with a user created one.



see the tutorial for a complete example.




void date_gen_phrase_strings(...)
  Parameters:
    input_collection_type

Sets new date generator phrase strings in date_gen_parser. The input collection is a vector of strings (for details on these strings see date generator formatter/parser documentation).







void short_weekday_names(...)
  Parameter:
    input_collection_type

Replace strings used when 'getting' short weekdays.



see the tutorial for a complete example.




void long_weekday_names(...)
  Parameter:
    input_collection_type

Replace strings used when 'getting' long weekdays.



see the tutorial for a complete example.




void short_month_names(...)
  Parameter:
    input_collection_type

Replace strings used when 'getting' short months.



see the tutorial for a complete example.




void long_month_names(...)
  Parameter:
    input_collection_type

Replace strings used when 'getting' long months.



see the tutorial for a complete example.




InItrT get(...)
  Common parameters for all 
  'get' functions:
    InItrT from
    InItrT to
    ios_base
  Unique parameter for 'get' funcs:
    gregorian object

There are 13 get functions in the date_input_facet. The common parameters are: an iterator pointing to the begining of the stream, an iterator pointing to the end of the stream, and an ios_base object. Each unique gregorian object has it's own get function. Each unique get function is described below.







InItrT get(..., date)

Gets a date object from the stream using the format set by format(...) or the default.



ss.str("2005-Jan-01");
ss >> d; // default format




InItrT get(..., month)

Gets a month object from the stream using the format set by month_format(...) or the default.



ss.str("Feb");
ss >> m; // default format




InItrT get(..., day_of_week)

Gets a day of week object from the stream using the format set by weekday_format(...) or the default.



ss.str("Sun");
ss >> dow; // default format




InItrT get(..., day)

Gets a day of month object from the stream as a two digit number.



"01" // January 1st




InItrT get(..., year)

Gets a year object from the stream as a number. The number of expected digits depends on the year format.



ss/str("2005");
ss >> y; // default format




InItrT get(..., days)

Gets a days object from the stream as a number.



ss.str("356");
ss >> dys; // a full year




InItrT get(..., date_period)

Gets a date_period from the stream. The format of the dates will use the format set by format(..) or the default date format. The type of period (open or closed range) and the delimiters used are those used by the period_parser.



see the tutorial for a complete example.




InItrT get(..., partial_date)

Gets a partial_date date_generator object from the stream. The month format used is set by month_format(..) or the default. The day of month is represented as a two digit number.



"01 Jan" // default formats
"01 January" // long month format




InItrT get(..., date_generator)
  Date Generator Type:
    nth_day_of_the_week_in_month

Gets a nth_day_of_the_week_in_month object from the stream. The month format is set by month_format(...) or the default. The weekday format is set by weekday_format(...) or the default. The remaining phrase elements are set in the date_generator_parser.



"third Fri in May" // defaults




InItrT get(..., date_generator)
  Date Generator Type:
    first_day_of_the_week_in_month

Gets a first_day_of_the_week_in_month object from the stream. The month format is set by month_format(...) or the default. The weekday format is set by weekday_format(...) or the default. The remaining phrase elements are set in the date_generator_parser.



"first Wed of Jun" // defaults




InItrT get(..., date_generator)
  Date Generator Type:
    last_day_of_the_week_in_month

Gets a last_day_of_the_week_in_month object from the stream. The month format is set by month_format(...) or the default. The weekday format is set by weekday_format(...) or the default. The remaining phrase elements are set in the date_generator_parser.



"last Tue of Mar" // defaults




InItrT get(..., date_generator)
  Date Generator Type:
    first_day_of_the_week_after

Gets a first_day_of_the_week_after object from the stream. The weekday format is set by weekday_format(...) or the default. The remaining phrase elements are set in the date_generator_parser.



"first Sat after" // defaults




InItrT get(..., date_generator)
  Date Generator Type:
    first_day_of_the_week_before

Gets a first_day_of_the_week_before object from the stream. The weekday format is set by weekday_format(...) or the default. The remaining phrase elements are set in the date_generator_parser.



"first Mon before" // defaults






  







Time Facet

Introduction -
  Construction -
  Accessors

Introduction


The boost::date_time::time_facet is an extension of the boost::date_time::date_facet. The time_facet is typedef'ed in the posix_time namespace as time_facet and wtime_facet. It is typedef'd in the local_time namespace as local_time_facet and wlocal_time_facet.
  



Construction



    









Syntax
Description






time_facet()

Default constructor





time_facet(...)
  Parameters:
    char_type* format
    period_formatter_type
    special_values_formatter_type
    date_gen_formatter_type

Format given will be used for time output. The remaining parameters are formatter objects. Further details on these objects can be found here. This constructor also provides default arguments for all parameters except the format. Therefore, time_facet("%H:%M:S %m %d %Y") will work.







  



Accessors



    The time_facet inherits all the public date_facet methods. Therefore, the date_facet methods are not listed here. Instead, they can be found by following this link.
    










Syntax
Description



Example






void time_duration_format(...)
  Parameter:
    char_type*

Sets the time_duration format. The time_duration format has the ability to display the sign of the duration. The '%+' flag will always display the sign. The '%-' will only display if the sign is negative. Currently the '-' and '+' characters are used to denote the sign.



f->time_duration_format("%+%H:%M");
// hours and minutes only w/ sign always displayed
time_duration td1(3, 15, 56);
time_duration td2(-12, 25, 32);
ss << td1; // "+03:15:56"
ss << td2; // "-12:25:56"
            




void set_iso_format()

Sets the date and time format to ISO.



f->set_iso_format();
// "%Y%m%dT%H%M%S%F%q"




void set_iso_extended_format()

Sets the date and time format to ISO Extended



f->set_iso_extended_format();
// "%Y-%m-%d %H:%M:%S%F%Q"




OutItrT put(...)
  Common parameters for all 
  'put' functions:
    OutItrT 
    ios_base
    char_type
  Unique parameter for 'put' funcs:
    posix_time object

There are 3 put functions in the time_facet. The common parameters are: an iterator pointing to the next item in the stream, an ios_base object, and the fill character. Each unique posix_time object has it's own put function. Each unique put function is described below.







OutItrT put(..., ptime)

Puts a ptime object into the stream using the format set by format(...) or the default.







OutItrT put(..., time_duration)

Puts a time_duration object into the stream using the format set by time_duration_format(...) or the default.







OutItrT put(..., time_period)

Puts a time_period into the stream. The format of the dates and times will use the format set by format(..) or the default date/time format. The type of period (open or closed range) and the delimiters used are those used by the period_formatter.









  







Time Input Facet

Introduction -
  Construction -
  Accessors

Introduction


The boost::date_time::time_input_facet is an extension of the date_input_facet. It is typedef'ed in the boost::posix_time namespace as time_input_facet and wtime_input_facet. It is typedef'ed in the boost::local_time namespace as local_time_input_facet and wlocal_time_input_facet.
  



Construction



    









Syntax
Description






time_input_facet()

Default constructor





time_input_facet(string_type)

Format given will be used for date/time input. All other formats will use their defaults.





time_input_facet(...)
  Parameters:
    string_type format
    format_date_parser_type
    special_values_parser_type
    period_parser_type
    date_gen_parser_type

Format given will be used for date/time input. The remaining parameters are parser objects. Further details on these objects can be found here.







  



Accessors



    The time_input_facet inherits all the public date_input_facet methods. Therefore, the date_input_facet methods are not listed here. Instead, they can be found by following this link.
    










Syntax
Description



Example






void set_iso_format()

Sets the time format to ISO



f->set_iso_format();
// "%Y%m%dT%H%M%S%F%q"
"20051225T132536.789-0700"




void set_iso_extended_format()

Sets the date format to ISO Extended



f->set_iso_extended_format();
// "%Y-%m-%d %H:%M:%S%F %Q"
"2005-12-25 13:25:36.789 -07:00"




void time_duration_format(...)
  Parameter:
    char_type*

Sets the time_duration format.



f->time_duration_format("%H:%M");
// hours and minutes only




InItrT get(...)
  Common parameters for all 
  'get' functions:
    InItrT from
    InItrT to
    ios_base
  Unique parameter for 'get' funcs:
    gregorian object

There are 3 get functions in the time_input_facet. The common parameters are: an iterator pointing to the begining of the stream, an iterator pointing to the end of the stream, and an ios_base object. Each unique gregorian object has it's own get function. Each unique get function is described below.







InItrT get(..., ptime)

Gets a ptime object from the stream using the format set by format(...) or the default.



ss.str("2005-Jan-01 13:12:01");
ss >> pt; // default format




InItrT get(..., time_duration)

Gets a time_duration object from the stream using the format set by time_duration_format(...) or the default.



ss.str("01:25:15.000123000");
ss >> td; // default format




InItrT get(..., time_period)

Gets a time_period from the stream. The format of the dates/times will use the format set by format(..) or the default date and time format. The type of period (open or closed range) and the delimiters used are those used by the period_parser.



see the tutorial for a complete example.






  







Date Time Formatter/Parser Objects



Date Time Formatter/Parser Objects

Periods |
  Date Generators |
  Special Values |
  Format Date Parser

Periods


The period_formatter and period_parser provide a uniform interface for the input and output of date_periods, time_periods, and in a future release, local_date_time_periods. The user has control over the delimiters, formats of the date/time components, and the form the period takes. The format of the date/time components is controlled via the date_time input and output facets.



Period Form


Periods are constructed with open ranged parameters. The first value is the starting point, and is included in the period. The end value is not included but immediately follows the last value: [begin/end). However, a period can be streamed as either an open range or a closed range.


[2003-Jan-01/2003-Dec-31] <-- period holding 365 days
[2003-Jan-01/2004-Jan-01) <-- period holding 365 days



Delimiters


There are four delimiters. The default values are




"\" - separator


"[" - start delimiter


")" - open range end delimiter


"]" - closed range end delimiter




A user can provide a custom set of delimiters. Custom delimiters may contain spaces.



Customization


The period form and delimiters can be set as construction parameters or by means of accessor functions. A custom period parser/formatter can then be used as a construction parameter to a new facet, or can be set in an existing facet via an accessor function.



Period Formatter/Parser Reference

  The complete class reference can be found here: Period Formatter Doxygen Reference and here: Period Parser Doxygen Reference

    



Period Formatter Construction



    









Syntax
Description





period_formatter(...)
  Parameters:
    range_display_options
    char_type*
    char_type*
    char_type*
    char_type*

NOTE: All five construction parameters have default values so this constructor also doubles as the default constructor. The range_display_options is a public type enum of the period_formatter class. The possible choices are AS_OPEN_RANGE or AS_CLOSED_RANGE. The closed range is the default. A period has three significant points: the begining, the last, and the end. A closed range period takes the form [begin,end), where an open range period takes the form [begin,last]. The four char_type* parameters are: the period separator, the start delimiter, the open range end delimiter, and the closed range end delimiter.






    



Period Formatter Accessors



    










Syntax
Description



Example






range_display_options range_option()

Returns the current setting for the range display (either AS_OPEN_RANGE or AS_CLOSED_RANGE).







void range_option(...)
  Parameter:
    range_display_options

Sets the option for range display (either AS_OPEN_RANGE or AS_CLOSED_RANGE).







void delimiter_strings(...)
  Parameters:
    string_type
    string_type
    string_type
    string_type

Set new delimiter strings in the formatter.



string beg("->| ");
string sep(" || ");
string opn(" ->|");
string clo(" |<-");
pf.delimiter_strings(beg, sep, 
                     opn, clo);




put_period_start_delimeter(...)
  Return Type:
    OutItrT
  Parameter:
    OutItrT

Puts the start delimiter into the stream at position pointed to by OutItrT parameter.







put_period_sepatator(...)
  Return Type:
    OutItrT
  Parameter:
    OutItrT

Puts the separator into the stream at position pointed to by OutItrT parameter.







put_period_end_delimeter(...)
  Return Type:
    OutItrT
  Parameter:
    OutItrT

Puts the end delimiter into the stream at position pointed to by OutItrT parameter.







OutItrT put_period(...)
  Parameters:
    OutItrT
    ios_base
    char_type
    period_type
    facet_type

Puts a period into the stream using the set values for delimiters, separator, and range display. The facet parameter is used to put the date (or time) objects of the period.









  



    



Period Parser Construction



    









Syntax
Description






period_parser(...)
  Parameters:
    period_range_option
    char_type*
    char_type*
    char_type*
    char_type*

NOTE: All five construction parameters have default values so this constructor also doubles as the default constructor. The period_range_option is a public type enum of the period_parser class. The possible choices are AS_OPEN_RANGE or AS_CLOSED_RANGE. The closed range is the default. A period has three significant points: the begining, the last, and the end. A closed range period takes the form [begin,end), where an open range period takes the form [begin,last]. The four char_type* parameters are: the period separator, the start delimiter, the open range end delimiter, and the closed range end delimiter.





period_parser(period_parser)

Copy constructor







    



Period Parser Accessors



    










Syntax
Description



Example






period_range_option range_option()

Returns the current setting for the period range (either AS_OPEN_RANGE or AS_CLOSED_RANGE).







void range_option(...)
  Parameter:
    period_range_option 

Sets the option for period range (either AS_OPEN_RANGE or AS_CLOSED_RANGE).







void delimiter_strings(...)
  Parameters:
    string_type
    string_type
    string_type
    string_type

Set new delimiter strings in the parser.



string beg("->| ");
string sep(" || ");
string opn(" ->|");
string clo(" |<-");
pp.delimiter_strings(beg, sep, 
                     opn, clo);




collection_type delimiter_strings()

Returns the set of delimiter strings currently held in the parser.







period_type get_period(...)
  Parameters:
    stream_itr_type
    stream_itr_type
    ios_base
    period_type
    duration_type
    facet_type

Parses a period from the stream. The iterator parameters point to the begining and end of the stream. The duration_type is relevant to the period type, for example: A date_period would use days as a duration_type. The period will be parsed according to the formats and strings found in the facet parameter.









  


_____________________________________________________



Date Generators


The date_generator formatter and parser provide flexibility by allowing the user to use custom "phrase elements". These phrase elements are the "in-between" words in the date_generators. For example, in the date_generator "Second Monday of March", "Second" and "of" are the phrase elements, where "Monday" and "March" are the date elements. Customization of the date elements is done with the facet. The order of the date and phrase elements cannot be changed. When parsing, all elements of the date_generator phrase must parse correctly or an ios_base::failure exception will be thrown.



Customization


The default "phrase_strings" are:
    



"first"
"second"
"third"
"fourth"
"fifth"
"last"
"before"
"after"
"of"




    A custom set of phrase_strings must maintain this order of occurance (Ex: "1st", "2nd", "3rd", "4th", "5th", "last", "prior", "past", "in").


 Examples using default phrase_strings and default facet formats for weekday & month: 


"first Tue of Mar"


And using custom phrase_strings: 


"1st Tue in Mar"



  


The custom set of phrase elements can be set as construction parameters or through an accessor function.A custom date_generator parser/formatter can then be used as a construction parameter to a new facet, or can be set in an existing facet via an accessor function.


IMPORTANT NOTE: Prior to 1.33, partial_date was output as "1 Jan" with a single *or* double digit number for the day. The new behavior is to *always* place a double digit number for the day - "01 Jan".



Date Generator Reference

  The complete class references can be found here: Date Generator Formatter Doxygen Reference and here: Date Generator Parser Doxygen Reference

    



Date Generator Formatter Construction



    









Syntax
Description






date_generator_formatter()

Uses the default date generator elements.





date_generator_formatter(...)
  Parameters:
    string_type first_element
    string_type second_element
    string_type third_element
    string_type fourth_element
    string_type fifth_element
    string_type last_element
    string_type before_element
    string_type after_element
    string_type of_element

Constructs a date_generator_formatter using the given element strings.







    



Date Generator Formatter Accessors



    










Syntax
Description



Example






void elements(...)
  Parameters:
    collection_type
    phrase_elements

Replace the current phrase elements with a collection of new ones. The phrase_elements parameter is an enum that indicates what the first element in the new collection is (defaults to first).



// col is a collection holding 
// "final", "prior", "following",
// and "in"
typedef date_generator_formatter dgf;                                  
dgf formatter();
formatter.elements(col, dgf::last);
// complete elements in dgf are now: 
"first", "second", "third", 
"fourth", "fifth", "final", 
"prior", "following", and "in"




put_partial_date(...)
  Return Type:
    facet_type::OutItrT
  Parameters:
    OutItrT next
    ios_base
    char_type fill
    partial_date
    facet_type

A put function for partial_date. This is a templated function that takes a facet_type as a parameter.



Put a partial_date => "dd Month".




put_nth_kday(...)
  Return Type:
    facet_type::OutItrT
  Parameters:
    OutItrT next
    ios_base
    char_type fill
    nth_kday_type
    facet_type

A put function for nth_kday_type. This is a templated function that takes a facet_type as a parameter.



Put an nth_day_of_the_week_in_month => "nth weekday of month".




put_first_kday(...)
  Return Type:
    facet_type::OutItrT
  Parameters:
    OutItrT next
    ios_base
    char_type fill
    first_kday_type
    facet_type

A put function for first_kday_type. This is a templated function that takes a facet_type as a parameter.



Put a first_day_of_the_week_in_month => "first weekday of month".




put_last_kday(...)
  Return Type:
    facet_type::OutItrT
  Parameters:
    OutItrT next
    ios_base
    char_type fill
    last_kday_type
    facet_type

A put function for last_kday_type. This is a templated function that takes a facet_type as a parameter.



Put a last_day_of_the_week_in_month => "last weekday of month".




put_kday_before(...)
  Return Type:
    facet_type::OutItrT
  Parameters:
    OutItrT next
    ios_base
    char_type fill
    kday_before_type
    facet_type

A put function for kday_before_type. This is a templated function that takes a facet_type as a parameter.



Put a first_day_of_the_week_before => "weekday before"




put_kday_after(...)
  Return Type:
    facet_type::OutItrT
  Parameters:
    OutItrT next
    ios_base
    char_type fill
    kday_after_type
    facet_type

A put function for kday_after_type. This is a templated function that takes a facet_type as a parameter.



Put a first_day_of_the_week_after => "weekday after".






  



    



Date Generator Parser Construction



    









Syntax
Description






date_generator_parser()

Uses the default date generator elements.





date_generator_parser(...)
  Parameter:
    date_generator_parser

Copy Constructor





date_generator_parser(...)
  Parameters:
    string_type first_element
    string_type second_element
    string_type third_element
    string_type fourth_element
    string_type fifth_element
    string_type last_element
    string_type before_element
    string_type after_element
    string_type of_element

Constructs a date_generator_parser using the given element strings.







    



Date Generator Parser Accessors



    










Syntax
Description



Example






void element_strings(...)
  Parameter:
    collection_type

Replace the set of date generator element string with a new set.







void element_strings(...)
  Parameters:
    string_type first
    string_type second
    string_type third
    string_type fourth
    string_type fifth
    string_type last
    string_type before
    string_type after
    string_type of

Replace the set of date generator elements with new values.







get_partial_date_type(...)
  Return Type:
    facet_type::partial_date_type
  Parameters:
    stream_itr_type next
    stream_itr_type str_end
    ios_base
    facet_type

A templated function that parses a date_generator from the stream.



Parses a partial_date => "dd Month".




get_nth_kday_type(...)
  Return Type:
    facet_type::nth_kday_type
  Parameters:
    stream_itr_type next
    stream_itr_type str_end
    ios_base
    facet_type

A templated function that parses a date_generator from the stream.



Parses an nth_day_of_the_week_in_month => "nth weekday of month".




get_first_kday_type(...)
  Return Type:
    facet_type::firat_kday_type
  Parameters:
    stream_itr_type next
    stream_itr_type str_end
    ios_base
    facet_type

A templated function that parses a date_generator from the stream.



Parses a first_day_of_the_week_in_month => "first weekday of month".




get_last_kday_type(...)
  Return Type:
    facet_type::last_kday_type
  Parameters:
    stream_itr_type next
    stream_itr_type str_end
    ios_base
    facet_type

A templated function that parses a date_generator from the stream.



Parses a last_day_of_the_week_in_month => "last weekday of month".




get_kday_before_type(...)
  Return Type:
    facet_type::kday_before_type
  Parameters:
    stream_itr_type next
    stream_itr_type str_end
    ios_base
    facet_type

A templated function that parses a date_generator from the stream.



Parses a first_day_of_the_week_before => "weekday before"




get_kday_after_type(...)
  Return Type:
    facet_type::kday_after_type
  Parameters:
    stream_itr_type next
    stream_itr_type str_end
    ios_base
    facet_type

A templated function that parses a date_generator from the stream.



Parses a first_day_of_the_week_after => "weekday after".






  


_____________________________________________________



Special Values


The date_time library uses five special_values. They are:
    



not_a_date_time
neg_infin
pos_infin
min_date_time
max_date_time




  


The default set of strings used to represent these types are: "not-a-date-time", "-infinity", "+infinity", "minimum-date-time", "maximum-date-time". When output, the min_date-time and max_date_time appear as normal date/time representations: "1400-Jan-01" and "9999-Dec-31" repectively.



Customization


The special values parser/formatter allows the user to set custom strings for these special values. These strings can be set as construction parameters to a new facet, or can be set in an existing facet via an accessor function.



Special Values Formatter/Parser Reference

  The complete class references can be found here: Special Values Formatter Doxygen Reference and here: Special Values Parser Doxygen Reference

    



Special Values Formatter Constructor



    









Syntax
Description






special_values_formatter()

Constructor uses defaults for special value strings.





special_values_formatter(...)
  Parameters:
    collection_type::iterator
    collection_type::iterator

Constructs using values in collection. NOTE: Only the first three strings of the collection will be used. Strings for minimum_date_time and maximum_date_time are ignored as those special values are output as normal dates/times.





special_values_formatter(...)
  Parameters:
    char_type*
    char_type*

Constructs special values formatter from an array of strings.







  



    



Special Values Formatter Accessors



    










Syntax
Description



Example






OutItrT put_special(...)
  Parameters:
    OutItrT next
    special_values value

Puts the given special value into the stream.



date d1(not_a_date_time);
date d2(minimum_date_time);
special_values_formatter formatter;
formatter.put_special(itr, d1); 
// Puts: "not-a-date-time"
formatter.put_special(itr, d2); 
// Puts: "1400-Jan-01"






  



    



Special Values Parser Constructor



    









Syntax
Description






special_values_parser()

 





special_values_parser(...)
  Parameters:
    collection_type::iterator
    collection_type::iterator

Constructs a special values parser using the strings in the collection.





special_values_parser(...)
  Parameter:
    scpecial_values_parser

Copy constructor.





special_values_parser(...)
  Parameters:
    string_type nadt_str
    string_type neg_inf_str
    string_type pos_inf_str
    string_type min_dt_str
    string_type max_dt_str

Constructs a special values parser using the supplied strings.







  



    



Special Values Parser Accessors



    










Syntax
Description



Example






void sv_strings(...)
  Parameters:
    string_type nadt_str
    string_type neg_inf_str
    string_type pos_inf_str
    string_type min_dt_str
    string_type max_dt_str

Replace the set of special value strings with the given ones.







bool match(...)
  Parameters:
    stream_itr_type beg
    stream_itr_type end
    match_results

Returns true if parse was successful. Upon a successful parse, mr.current_match will be set an int values corresponding to the equivalent special_value.



// stream holds "maximum_date_time"
typedef special_values_parser svp;
svp parser;
svp::match_results mr;
if(parser.match(itr, str_end, mr)) {
  d = date(static_cast<special_values>(
           mr.match_results))
} else {
  // error, failed parse
}
// d == "9999-Dec-31"






  


_____________________________________________________



Format Date Parser


The format date parser is the object that holds the strings for months and weekday names, as well as their abbreviations. Custom sets of strings can be set at construction time, or, the strings in an existing format_date_parser can be replaced through accessor functions. Both the constructor and the accessor functions take a vector of strings as their arguments.



Format Date Parser Reference

  The complete class reference can be found here: Doxygen Reference

    



Format Date Parser Constructor



    









Syntax
Description






format_date_parser(...)
                Parameters:
                string_type format
                std::locale

Creates a parser that uses the given format for parsing dates (in those functions where there is no format parameter). The names and abbreviations used are extracted from the given locale.





format_date_parser(...)
  Parameters:
    string_type format
    input_collection_type
    input_collection_type
    input_collection_type
    input_collection_type

Creates a parser from using the given components. The input_collection_type parameters are for: short month names, long month names, short weekday names, and long weekday names (in that order). These collections must contain values for every month and every weekday (begining with January and Sunday).





format_date_parser(...)
  Parameters:
    format_date_parser

Copy Constructor







  



    



Format Date Parser Accessors



    










Syntax
Description



Example






string_type format()

Returns the format that will be used when parsing dates in those functions where there is no format parameter.







void format(string_type)

Sets the format that will be used when parsing dates in those functions where there is no format parameter.







void short_month_names(...)
  Parameter:
    input_collection_type names

Replace the short month names used by the parser. The collection must contain values for each month, starting with January.







void long_month_names(...)
  Parameter:
    input_collection_type names

Replace the long month names used by the parser. The collection must contain values for each month, starting with January.







void short_weekday_names(...)
  Parameter:
    input_collection_type names

Replace the short weekday names used by the parser. The collection must contain values for each weekday, starting with Sunday.







void long_weekday_names(...)
  Parameter:
    input_collection_type names

Replace the long weekday names used by the parser. The collection must contain values for each weekday, starting with Sunday.







date_type parse_date(...)
  Parameters:
    string_type input
    string_type format 
    special_values_parser

Parse a date from the given input using the given format.



string inp("2005-Apr-15");
string format("%Y-%b-%d");
date d;
d = parser.parse_date(inp, 
                      format,
                      svp);
// d == 2005-Apr-15




date_type parse_date(...)
  Parameters:
    istreambuf_iterator input
    istreambuf_iterator str_end
    special_values_parser

Parse a date from stream using the parser's format.







date_type parse_date(...)
  Parameters:
    istreambuf_iterator input
    istreambuf_iterator str_end
    string_type format
    special_values_parser

Parse a date from stream using the given format.



// stream holds "2005-04-15"
string format("%Y-%m-%d");
date d;
d = parser.parse_date(itr, 
                      str_end, 
                      format,
                      svp);
// d == 2005-Apr-15




month_type parse_month(...)
  Parameters:
    istreambuf_iterator input
    istreambuf_iterator str_end
    string_type format

Parses a month from stream using given format. Throws bad_month if unable to parse.



// stream holds "March"
string format("%B");
greg_month m;
m = parser.parse_month(itr, 
                       str_end, 
                       format);
// m == March




day_type parse_day_of_month(...)
  Parameters:
    istreambuf_iterator input
    istreambuf_iterator str_end

Parses a day_of_month from stream. The day must appear as a two digit number (01-31), or a bad_day_of_month will be thrown.



// stream holds "01"
greg_day d;
d = parser.parse_day_of_month(itr, 
                       str_end);
// d == 1st




day_type parse_var_day_of_month(...)
  Parameters:
    istreambuf_iterator input
    istreambuf_iterator str_end

Parses a day_of_month from stream. The day must appear as a one or two digit number (1-31), or a bad_day_of_month will be thrown.



// stream holds "1"
greg_day d;
d = parser.parse_var_day_of_month(itr, 
                       str_end);
// d == 1st




day_of_week_type parse_weekday(...)
  Parameters:
    istreambuf_iterator input
    istreambuf_iterator str_end
    string_type format

Parse a weekday from stream according to the given format. Throws a bad_weekday if unable to parse.



// stream holds "Tue"
string format("%a");
greg_weekday wd;
wd = parser.parse_weekday(itr, 
                          str_end, 
                          format);
// wd == Tuesday




year_type parse_year(...)
  Parameters:
    istreambuf_iterator input
    istreambuf_iterator str_end
    string_type format

Parse a year from stream according to given format. Throws bad year if unable to parse.



// stream holds "98"
string format("%y");
greg_year y;
y = parser.parse_year(itr, 
                      str_end, 
                      format);
// y == 1998






  







Date Time IO Tutorial



Date Time IO Tutorial

Basic Use |
  Format Strings |
  Content Strings |
  Special Values |
  Date/Time Periods |
  Date Generators

Basic Use


Facets are automatically imbued when operators '>>' and '<<' are called. The list of date_time objects that can be streamed are:



Gregorian



    date, 
    days, 
    date_period, 
    greg_month, 
    greg_weekday, 
    greg_year, 
    partial_date, 
    nth_day_of_the_week_in_month, 
    first_day_of_the_week_in_month, 
    last_day_of_the_week_in_month, 
    first_day_of_the_week_after, 
    first_day_of_the_week_before
  



Posix_time



    ptime, 
    time_period, 
    time_duration
  



Local_time



    local_date_time
  



    The following example is of the basic use of the new IO code, utilizing all the defaults. (this example can be found in the libs/date_time/examples/tutorial directory)
  


    
  date d(2004, Feb, 29);
  time_duration td(12,34,56,789);
  stringstream ss;
  ss << d << ' ' << td;
  ptime pt(not_a_date_time);
  cout << pt << endl; // "not-a-date-time"
  ss >> pt;
  cout << pt << endl; // "2004-Feb-29 12:34:56.000789"
  ss.str("");
  ss << pt << " EDT-05EDT,M4.1.0,M10.5.0";
  local_date_time ldt(not_a_date_time);
  ss >> ldt;
  cout << ldt << endl; // "2004-Feb-29 12:34:56.000789 EDT"
    
  


This example used the default settings for the input and output facets. The default formats are such that interoperability like that shown in the example is possible. NOTE: Input streaming of local_date_time can only be done with a posix time zone string. The default output format uses a time zone abbreviation. The format can be changed so out and in match (as we will see later in this tutorial).



Format Strings


The format strings control the order, type, and style of the date/time elements used. The facets provide some predefined formats (iso_format_specifier, iso_format_extended_specifier, and default_date_format) but the user can easily create their own.

  (continued from previous example)
  
    
  local_time_facet* output_facet = new local_time_facet();
  local_time_input_facet* input_facet = new local_time_input_facet();
  ss.imbue(locale(locale::classic(), output_facet));
  ss.imbue(locale(ss.getloc(), input_facet));
  
  output_facet->format("%a %b %d, %H:%M %z");
  ss.str("");
  ss << ldt;
  cout << ss.str() << endl; // "Sun Feb 29, 12:34 EDT"

  output_facet->format(local_time_facet::iso_time_format_specifier);
  ss.str("");
  ss << ldt;
  cout << ss.str() << endl; // "20040229T123456.000789-0500"
 
  output_facet->format(local_time_facet::iso_time_format_extended_specifier);
  ss.str("");
  ss << ldt;
  cout << ss.str() << endl; // "2004-02-29 12:34:56.000789-05:00"
    
  


Format strings are not limited to date/time elements. Extra verbiage can be placed in a format string. NOTE: When extra verbiage is present in an input format, the data being input must also contain the exact verbiage.

  (continued from previous example)
  
    
  // extra words in format
  string my_format("The extended ordinal time %Y-%jT%H:%M can also be \
  represented as %A %B %d, %Y");
  output_facet->format(my_format.c_str());
  input_facet->format(my_format.c_str());
  ss.str("");
  ss << ldt;
  cout << ss.str() << endl;

  // matching extra words in input 
  ss.str("The extended ordinal time 2005-128T12:15 can also be \
  represented as Sunday May 08, 2005");
  ss >> ldt;
  cout << ldt << endl;
    
  



Content Strings


So far we've shown how a user can achieve a great deal of customization with very little effort by using formats. Further customization can be achieved through user defined elements (ie strings). The elements that can be customized are: Special value names, month names, month abbreviations, weekday names, weekday abbreviations, delimiters of the date/time periods, and the phrase elements of the date_generators.


The default values for these are as follows:



Special values



    not-a-date-time, 
    -infinity, 
    +infinity, 
    minimum-date-time, 
    maximum-date-time
  



Months



    English calendar and three letter abbreviations
  



Weekdays



    English calendar and three letter abbreviations
  



Date generator phrase elements



    first, 
    second, 
    third, 
    fourth, 
    fifth, 
    last, 
    before, 
    after, 
    of
  


NOTE: We've shown earlier that the components of a date/time representation can be re-ordered via the format string. This is not the case with date_generators. The elements themselves can be customized but their order cannot be changed.



Content Strings


To illustrate the customization possibilities we will use custom strings for months and weekdays (we will only use long names, is all lowercase, for this example).

  (continued from previous example)
  
    
  // set up the collections of custom strings.
  // only the full names are altered for the sake of brevity
  string month_names[12] = { "january", "february", "march", 
                             "april", "may", "june", 
                             "july", "august", "september", 
                             "october", "november", "december" };
  vector<string> long_months(&month_names[0], &month_names[12]);
  string day_names[7] = { "sunday", "monday", "tuesday", "wednesday", 
                          "thursday", "friday", "saturday" };
  vector<string> long_days(&day_names[0], &day_names[7]);
  
  //  create date_facet and date_input_facet using all defaults
  date_facet* date_output = new date_facet();
  date_input_facet* date_input = new date_input_facet();
  ss.imbue(locale(ss.getloc(), date_output)); 
  ss.imbue(locale(ss.getloc(), date_input));

  // replace names in the output facet
  date_output->long_month_names(long_months);
  date_output->long_weekday_names(long_days);
  
  // replace names in the input facet
  date_input->long_month_names(long_months);
  date_input->long_weekday_names(long_days);
  
  // customize month, weekday and date formats
  date_output->format("%Y-%B-%d");
  date_input->format("%Y-%B-%d");
  date_output->month_format("%B"); // full name
  date_input->month_format("%B"); // full name
  date_output->weekday_format("%A"); // full name
  date_input->weekday_format("%A"); // full name

  ss.str("");
  ss << greg_month(3);
  cout << ss.str() << endl; // "march"
  ss.str("");
  ss << greg_weekday(3);
  cout << ss.str() << endl; // "tuesday"
  ss.str("");
  ss << date(2005,Jul,4);
  cout << ss.str() << endl; // "2005-july-04"
    
  



Special Values


Customizing the input and output of special values is best done by creating a new special_values_parser and special_values_formatter. The new strings can be set at construction time (as in the example below).

  (continued from previous example)
  
    
  // reset the formats to defaults
  output_facet->format(local_time_facet::default_time_format);
  input_facet->format(local_time_input_facet::default_time_input_format);

  // create custom special_values parser and formatter objects
  // and add them to the facets
  string sv[5] = {"nadt","neg_inf", "pos_inf", "min_dt", "max_dt" };
  vector<string> sv_names(&sv[0], &sv[5]);
  special_values_parser sv_parser(sv_names.begin(), sv_names.end());
  special_values_formatter sv_formatter(sv_names.begin(), sv_names.end());
  output_facet->special_values_formatter(sv_formatter);
  input_facet->special_values_parser(sv_parser);

  ss.str("");
  ldt = local_date_time(not_a_date_time);
  ss << ldt;
  cout << ss.str() << endl; // "nadt"
  
  ss.str("min_dt");
  ss >> ldt;
  ss.str("");
  ss << ldt;
  cout << ss.str() << endl; // "1400-Jan-01 00:00:00 UTC"
    
  


NOTE: even though we sent in strings for min and max to the formatter, they are ignored because those special values construct to actual dates (as shown above).



Date/Time Periods


Customizing the input and output of periods is best done by creating a new period_parser and period_formatter. The new strings can be set at construction time (as in the example below).

  (continued from previous example)
  
    
  // all formats set back to defaults (not shown for brevity)

  // create our date_period
  date_period dp(date(2005,Mar,1), days(31)); // month of march

  // custom period formatter and parser
  period_formatter per_formatter(period_formatter::AS_OPEN_RANGE, 
                                 " to ", "from ", " exclusive", " inclusive" );
  period_parser per_parser(period_parser::AS_OPEN_RANGE, 
                           " to ", "from ", " exclusive" , "inclusive" );
  
  // default output
  ss.str("");
  ss << dp;
  cout << ss.str() << endl; // "[2005-Mar-01/2005-Mar-31]"
 
  // add out custom parser and formatter to  the facets
  date_output->period_formatter(per_formatter);
  date_input->period_parser(per_parser);
  
  // custom output
  ss.str("");
  ss << dp;
  cout << ss.str() << endl; // "from 2005-Feb-01 to 2005-Apr-01 exclusive"
    
  



Date Generators


Customizing the input and output of date_generators is done by replacing the existing strings (in the facet) with new strings.


NOTE: We've shown earlier that the components of a date/time representation can be re-ordered via the format string. This is not the case with date_generators. The elements themselves can be customized but their order cannot be changed.

  (continued from previous example)
  
    
  // custom date_generator phrases
  string dg_phrases[9] = { "1st", "2nd", "3rd", "4th", "5th", 
                           "final", "prior to", "following", "in" };
  vector<string> phrases(&dg_phrases[0], &dg_phrases[9]);

  // create our date_generator
  first_day_of_the_week_before d_gen(Monday);

  // default output
  ss.str("");
  ss << d_gen;
  cout << ss.str() << endl; // "Mon before"
 
  // add our custom strings to the date facets
  date_output->date_gen_phrase_strings(phrases);
  date_input->date_gen_element_strings(phrases);
  
  // custom output
  ss.str("");
  ss << d_gen;
  cout << ss.str() << endl; // "Mon prior to"
    
  








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