boost date time UTC versus local time

boost_date_time.cpp

#include <iostream>
#include <string>
#include "boost/date_time/local_time/local_time.hpp"
#include "boost/date_time/c_local_time_adjustor.hpp"

boost::posix_time::time_duration get_utc_offset(const boost::posix_time::ptime& time_stamp)
{
    using boost::posix_time::ptime;
    const ptime local_time = boost::date_time::c_local_adjustor<ptime>::utc_to_local(time_stamp);
    return local_time - time_stamp;
}

std::wstring get_utc_offset_string(const boost::posix_time::ptime& utc_time_stamp)
{
    const boost::posix_time::time_duration td = get_utc_offset(utc_time_stamp);
    const wchar_t fillChar = L'0';
    const wchar_t timeSeparator = L':';
    
    std::wostringstream out;
    out << (td.is_negative() ? L'-' : L'+');
    out << std::setw(2) << std::setfill(fillChar)
    << boost::date_time::absolute_value(td.hours());
    out << L':';
    out << std::setw(2) << std::setfill(fillChar)
    << boost::date_time::absolute_value(td.minutes());
    return out.str();
}

int main ()
{
    using namespace std;
    using namespace boost::posix_time;
    
    typedef boost::local_time::local_date_time time_t;
    typedef boost::local_time::time_zone_ptr time_zone_t;
    
    time_t now(second_clock::local_time(), time_zone_t());
    
    std::cout << "Now is " << now.local_time() << std::endl;

    const ptime utc_now = second_clock::universal_time();
    
    const wstring offset = get_utc_offset_string(utc_now);
    wcout << "UTC offset is " << offset.c_str() << endl;
    
    return 0;
}