1 /* This example demonstrates the use of the time zone database and
2 * local time to calculate the number of seconds since the UTC
3 * time_t epoch 1970-01-01 00:00:00. Note that the selected timezone
4 * could be any timezone supported in the time zone database file which
5 * can be modified and updated as needed by the user.
6 *
7 * To solve this problem the following steps are required:
8 * 1) Get a timezone from the tz database for the local time
9 * 2) Construct a local time using the timezone
10 * 3) Construct a posix_time::ptime for the time_t epoch time
11 * 4) Convert the local_time to utc and subtract the epoch time
12 *
13 */
14
15 #include "boost/date_time/local_time/local_time.hpp"
16 #include <iostream>
17
main()18 int main()
19 {
20 using namespace boost::gregorian;
21 using namespace boost::local_time;
22 using namespace boost::posix_time;
23
24 tz_database tz_db;
25 try {
26 tz_db.load_from_file("../data/date_time_zonespec.csv");
27 }catch(const data_not_accessible& dna) {
28 std::cerr << "Error with time zone data file: " << dna.what() << std::endl;
29 exit(EXIT_FAILURE);
30 }catch(const bad_field_count& bfc) {
31 std::cerr << "Error with time zone data file: " << bfc.what() << std::endl;
32 exit(EXIT_FAILURE);
33 }
34
35 time_zone_ptr nyc_tz = tz_db.time_zone_from_region("America/New_York");
36 date in_date(2004,10,04);
37 time_duration td(12,14,32);
38 // construct with local time value
39 // create not-a-date-time if invalid (eg: in dst transition)
40 local_date_time nyc_time(in_date,
41 td,
42 nyc_tz,
43 local_date_time::NOT_DATE_TIME_ON_ERROR);
44
45 std::cout << nyc_time << std::endl;
46
47 ptime time_t_epoch(date(1970,1,1));
48 std::cout << time_t_epoch << std::endl;
49
50 // first convert nyc_time to utc via the utc_time()
51 // call and subtract the ptime.
52 time_duration diff = nyc_time.utc_time() - time_t_epoch;
53
54 //Expected 1096906472
55 std::cout << "Seconds diff: " << diff.total_seconds() << std::endl;
56
57 }
58
59
60 /* Copyright 2005: CrystalClear Software, Inc
61 * http://www.crystalclearsoftware.com
62 *
63 * Subject to the Boost Software License, Version 1.0.
64 * (See accompanying file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)
65 */
66