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std::time_get::get_date, std::time_get::do_get_date

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< cpp‎ | locale‎ | time get
Revision as of 03:09, 3 June 2013 by P12 (Talk | contribs)

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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 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.

Contents

[edit] 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

[edit] Return value

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

[edit] 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.

[edit] Example

#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(
            std::istreambuf_iterator<char>(str),
            std::istreambuf_iterator<char>(),
            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::istreambuf_iterator<char>(),
                  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

[edit] See also

(C++11)
parses a date/time value of specified format
(function template) [edit]