std::time_get<CharT,InputIt>::get_date,std::time_get<CharT,InputIt>::do_get_date (3) - Linux Man Pages

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

NAME

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

Synopsis

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

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 the same format as

"%x" (until C++11)
"%d/%m/%y", "%m/%d/%y", "%y/%m/%d", and "%y/%d/%m", depending on date_order() (since C++11)

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;
      std::istreambuf_iterator<char> ret =
          std::use_facet<std::time_get<char>>(str.getloc()).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