[Boost-users] [date_time] Decoding ISO 8601 strings with timezones?

1 May 2010

      Hi all,

I'm trying to decode ISO strings into ptime values. But when I initialize what should be two equivalent ptimes, one in UTC and the other with a timezone designation, the resulting ptimes do not compare. It's as if the ISO extended format input facet is ignoring timezone values. I'm using boost 1.42.0.

I tried instancing an input facet with "%Y-%m-%dT%H:%M:%S%F%Q" instead of calling set_iso_extended_format, but this didn't work either.

Can someone suggest a solution?

Also, all the sample code I've seen in this area allocates a time_input_facet but does not delete it. Does the stream take care of deallocating the input facet when it goes out of scope, or will this result in a memory leak?

Here's the code and resulting assert output:

--snip--
ptime from_iso_extended_string(const string& inDateString)
{
	// If we get passed a zero length string, then return the "not a date" value.
	if (inDateString.empty())
	{
		return not_a_date_time;
	}

	// Use the ISO extended input facet to interpret the string.
	std::stringstream ss; 
	time_input_facet* input_facet = new time_input_facet(); 
	input_facet->set_iso_extended_format(); 
	ss.imbue(std::locale(ss.getloc(), input_facet)); 
	ss.str(inDateString); 
	ptime timeFromString; 
	ss >> timeFromString; 

	return timeFromString;
}

void boostTimeTest(void)
{
	cout << "Test decoding an ISO 8601 string with different timezones for equivalency:" << endl;
	string utcTimeStr("2010-05-01T18:00:00.000Z");
	string localTimeStr("2010-05-01T11:00:00.000-07:00");
	ptime utcTime = from_iso_extended_string(utcTimeStr);
	ptime localTime = from_iso_extended_string(localTimeStr);
	cout << "  Original utc string:   " << utcTimeStr << endl;
	cout << "  Decoded utc string:    " << to_iso_extended_string(utcTime) << endl;
	cout << "  Original local string: " << localTimeStr << endl;
	cout << "  Decoded local string:  " << to_iso_extended_string(localTime) << endl;

	// The following asserts because the resulting ptimes are not equivalent
	assert(utcTime == localTime);
}

--------------------------------------------
Test decoding an ISO 8601 string with different timezones for equivalency:
  Original utc string:   2010-05-01T18:00:00.000Z
  Decoded utc string:    2010-05-01T18:00:00
  Original local string: 2010-05-01T11:00:00.000-07:00
  Decoded local string:  2010-05-01T11:00:00
Assertion failed: (utcTime == localTime), function boostTimeTest

--snip--

Best,
--
Allen Cronce