Question

I want to convert a boost::posix_time::ptime to a boost::local_time::local_date_time using a timezone without daylight saving time only specified by it’s offset to UTC. I am using boost 1.47.0.

Currently I’m trying to create a boost::local_time::custom_time_zone (a.k.a custom_time_zone_base<char>). The only constructor of that class template is the follows:

custom_time_zone_base(
    const time_zone_names& zone_names,   
    const time_duration_type& utc_offset,
    const dst_adjustment_offsets& dst_shift,
    boost::shared_ptr<dst_calc_rule> calc_rule);

What should I supply as the dst_shift and calc_rule arguments? Or is there another class that better suits my needs, as I’m also supplying a zone_names as a boost::local_time::time_zone_names initialized with 4 empty strings.

Answer 1

The example in the date time docs shows you how to create a custom time zone without DST. You can see it at http://www.boost.org/doc/libs/1_47_0/doc/html/date_time/examples.html#date_time.examples.simple_time_zone.

Look at the code for the phx_1 timezone. You basically pass in a dst_adjustment_offsets initialized to three copies of time_duration(0,0,0) (3rd parameter) and pass in an empty shared pointer for the calculation rules (4th parameter).

(From the examples:)

// create more dependent objects for a non-dst custom_time_zone
time_zone_names tzn2("Mountain Standard Time", "MST", "", ""); // no dst means empty dst strings
time_duration utc_offset2(-7,0,0);
dst_adjustment_offsets adj_offsets2(time_duration(0,0,0), 
                                    time_duration(0,0,0), 
                                    time_duration(0,0,0));
// no dst means we need a null pointer to the rules
shared_ptr<dst_calc_rule> phx_rules;

// create the custom_time_zones
time_zone_ptr phx_1(new custom_time_zone(tzn2, utc_offset2, 
                                         adj_offsets2, phx_rules));