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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.
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
//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"
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 flags marked with a hash sign (#) are implemented by system locale and are known to be missing on some platforms. The first table is for dates, and the second table is for times.
| 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" |
| 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" | |
%H |
The hour as a decimal number using a 24-hour clock (range 00 to 23). |
%I ! |
The hour as a decimal number using a 12-hour clock (range 01 to 12). |
%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. |
%M |
The minute as a decimal number (range 00 to 59). |
%O |
The number of hours in a time duration as a decimal number (range 0 to max. representable duration); single digits are preceded by a zero. |
%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 have a platform-dependent behavior. These may not be supported everywhere.
! Signifies flags that currently do not work for input.
The following table lists the available facets.
* These links lead to the time_facet and time_input_facet reference sections. They are not actual classes but typedefs.
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 |
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.
| 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. |
| 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 |
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.
| 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. |
| 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 |
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.
| 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. |
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. |
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.
| 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. |
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. |
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.
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
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.
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 Doxygen Reference and here: Period Parser Doxygen Reference
| 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. |
| 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. |
| 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 |
| 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. |
_____________________________________________________
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.
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 Formatter Doxygen Reference and here: Date Generator Parser Doxygen Reference
| 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. |
| 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". |
| 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. |
| 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". |
_____________________________________________________
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.
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 Doxygen Reference and here: Special Values Parser Doxygen Reference
| 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. |
| 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" |
| 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. |
| 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" |
_____________________________________________________
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.
Doxygen Reference
| 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 |
| 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 |
Facets are automatically imbued when operators '>>' and '<<' are called. The list of date_time objects that can be streamed are:
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
ptime,
time_period,
time_duration
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).
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;
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:
not-a-date-time,
-infinity,
+infinity,
minimum-date-time,
maximum-date-time
English calendar and three letter abbreviations
English calendar and three letter abbreviations
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.
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"
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).
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"
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"