"20170101" gives surprising result parsed as extended ISO 8601

[Thomas Guest <thomas.guest@…>]

#include <locale>
#include <iostream>
#include <sstream>
#include <boost/date_time/gregorian/gregorian.hpp>

int main()
{
	std::string value = "20170105";

	boost::gregorian::date d;

	auto * f = new boost::gregorian::date_input_facet();
	f->set_iso_extended_format();

	std::stringstream ss;
	std::locale loc(std::locale::classic(), f);
	ss.imbue(loc);
	ss << value;
	ss >> d;

	std::cout << value << " => " << d << '\n';
	return 0;
}

When I run this I get:

20170105 => 2017-Oct-01

I expected an exception to be raised.

[Thomas Guest <thomas.guest@…>]

Apologies - version should be 1.65.1

[James E. King, III]

I just added this test to testdate_input_facet and using Boost 1.66.0 with msvc-14.1 it works properly. You did not enable exceptions in your example. Before calling imbue, you want to call:

    ss.exceptions(std::ios_base::failbit); // turn on exceptions

if you want an exception to be raised.

Example (add this to the testdate_input_facet unit test to see it work):

  // prove trac 13280 on extended iso format is behaving properly
  {
    std::string value = "20171221";
    date_input_facet *f13280_bad = new date_input_facet();
    f13280_bad->set_iso_extended_format();
    std::stringstream s13280_bad;
    s13280_bad.imbue(std::locale(s13280_bad.getloc(), f13280_bad));
    s13280_bad << value;
    boost::gregorian::date d13280_bad;
    check("extended ISO with YYYYMMDD sets failbit", 
          failure_test(d13280_bad, value, f13280_bad));
    check("extended iso with YYYYMMDD is not a date", 
          d13280_bad.is_not_a_date());
  }

[James E. King, III]

The documentation is clear on this one as well:

http://www.boost.org/doc/libs/1_66_0/doc/html/date_time/date_time_io.html

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.