std::time_get<CharT,InputIt>::get_date, std::time_get<CharT,InputIt>::do_get_date

Defined in header `<locale>`
public: iter_type get_date( iter_type beg, iter_type end, std::ios_base& str, std::ios_base::iostate& err, std::tm* t ) const;	(1)
protected: virtual iter_type do_get_date( iter_type beg, iter_type end, std::ios_base& str, std::ios_base::iostate& err, std::tm* t ) const;	(2)

1) Public member function, calls the protected virtual member function do_get_date of the most derived class.

2) Reads successive characters from the sequence [beg, end) and parses out the calendar date value using the default format expected by this locale, which is determined as

date_order()	Format
`no_order`	"%m/%d/%y"
`dmy`	"%d/%m/%y"
`mdy`	"%m/%d/%y"
`ymd`	"%y/%m/%d"
`ydm`	"%y/%d/%m"

as used by the functions std::get_time(), get(), and the POSIX function strptime().

The parsed date is stored in the corresponding fields of the std::tm structure pointed to by the argument t.

If the end iterator is reached before a valid date is read, the function sets std::ios_base::eofbit in err. If a parsing error is encountered, the function sets std::ios_base::failbit in err.

Parameters

beg	-	iterator designating the start of the sequence to parse
end	-	one past the end iterator for the sequence to parse
str	-	a stream object that this function uses to obtain locale facets when needed, e.g. std::ctype to skip whitespace or std::collate to compare strings
err	-	stream error flags object that is modified by this function to indicate errors
t	-	pointer to the std::tm object that will hold the result of this function call

Return value

Iterator pointing one past the last character in [beg, end) that was recognized as a part of a valid date.

Notes

For the alphabetic components of the default date format (if any), this function is usually case-insensitive.

If a parsing error is encountered, most implementations of this function leave *t unmodified.

The implementation may support other date formats besides the ones required by the standard.

Example

Run this code

#include <iostream>
#include <locale>
#include <sstream>
#include <iterator>
#include <ctime>
 
void try_get_date(const std::string& s)
{
    std::cout << "Parsing the date out of '" << s
              << "' in the locale " << std::locale().name() << '\n';
    std::istringstream str(s);
    std::ios_base::iostate err = std::ios_base::goodbit;
 
    std::tm t;
    const std::time_get<char>& facet = std::use_facet<std::time_get<char>>(str.getloc());
    std::istreambuf_iterator<char> ret = facet.get_date({str}, {}, str, err, &t);
    str.setstate(err);
 
    if (str)
    {
        std::cout << "Day: "   << t.tm_mday << ' '
                  << "Month: " << t.tm_mon + 1 << ' '
                  << "Year: "  << t.tm_year + 1900 << '\n';
    }
    else
    {
        std::cout << "Parse failed. Unparsed string: ";
        std::copy(ret, {}, std::ostreambuf_iterator<char>(std::cout));
        std::cout << '\n';
    }
}
int main()
{
    std::locale::global(std::locale("en_US.utf8"));
    try_get_date("02/01/2013");
    try_get_date("02-01-2013");
 
    std::locale::global(std::locale("ja_JP.utf8"));
    try_get_date("2013年02月01日");
}

Output:

Parsing the date out of '02/01/2013' in the locale en_US.utf8
Day: 1 Month: 2 Year: 2013
Parsing the date out of '02-01-2013' in the locale en_US.utf8
Parse failed. Unparsed string: -01-2013
Parsing the date out of '2013年02月01日' in the locale ja_JP.utf8
Day: 1 Month: 2 Year: 2013

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 248	C++98	`eofbit` was not set upon reaching the end iterator	sets `eofbit` if a valid date has not been read
LWG 461	C++98	`do_get_date` needed to parse localized date representation	parses with the format determined by date_order()

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Member functions
time_get::time_get
time_get::~time_get
time_get::date_ordertime_get::do_date_order
time_get::get_timetime_get::do_get_time
time_get::get_datetime_get::do_get_date
time_get::get_weekdaytime_get::do_get_weekday
time_get::get_monthnametime_get::do_get_monthname
time_get::get_yeartime_get::do_get_year
time_get::gettime_get::do_get