ceph/src/boost/libs/date_time/xmldoc/ex_local_utc_conversion.xml

   1 <?xml version="1.0" encoding="utf-8"?>
   2 <!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
   3 "../../../tools/boostbook/dtd/boostbook.dtd">
   4
   5 <!-- Copyright (c) 2001-2004 CrystalClear Software, Inc.
   6      Subject to the Boost Software License, Version 1.0.
   7      (See accompanying file LICENSE_1_0.txt or  http://www.boost.org/LICENSE_1_0.txt)
   8 -->
   9
  10 <section id="date_time.examples.local_utc_conversion">
  11   <title>Local to UTC Conversion</title>
  12
  13   <para>
  14     Demonstrate utc to local and local to utc calculations including dst.
  15   </para>
  16   <programlisting>
  17     <![CDATA[
  18
  19   /* Demonstrate conversions between a local time and utc
  20    * Output:
  21    *
  22    * UTC <--> New York while DST is NOT active (5 hours)
  23    * 2001-Dec-31 19:00:00 in New York is 2002-Jan-01 00:00:00 UTC time
  24    * 2002-Jan-01 00:00:00 UTC is 2001-Dec-31 19:00:00 New York time
  25    *
  26    * UTC <--> New York while DST is active (4 hours)
  27    * 2002-May-31 20:00:00 in New York is 2002-Jun-01 00:00:00 UTC time
  28    * 2002-Jun-01 00:00:00 UTC is 2002-May-31 20:00:00 New York time
  29    *
  30    * UTC <--> Arizona (7 hours)
  31    * 2002-May-31 17:00:00 in Arizona is 2002-Jun-01 00:00:00 UTC time
  32    */
  33
  34   #include "boost/date_time/posix_time/posix_time.hpp"
  35   #include "boost/date_time/local_time_adjustor.hpp"
  36   #include "boost/date_time/c_local_time_adjustor.hpp"
  37   #include <iostream>
  38
  39   int
  40   main()
  41   {
  42     using namespace boost::posix_time;
  43     using namespace boost::gregorian;
  44
  45     //This local adjustor depends on the machine TZ settings-- highly dangerous!
  46     typedef boost::date_time::c_local_adjustor<ptime> local_adj;
  47     ptime t10(date(2002,Jan,1), hours(7));
  48     ptime t11 = local_adj::utc_to_local(t10);
  49     std::cout << "UTC <--> Zone base on TZ setting" << std::endl;
  50     std::cout << to_simple_string(t11) << " in your TZ is "
  51               << to_simple_string(t10) << " UTC time "
  52               << std::endl;
  53     time_duration td = t11 - t10;
  54     std::cout << "A difference of: "
  55               << to_simple_string(td) << std::endl;
  56
  57
  58     //eastern timezone is utc-5
  59     typedef boost::date_time::local_adjustor<ptime, -5, us_dst> us_eastern;
  60
  61     ptime t1(date(2001,Dec,31), hours(19)); //5 hours b/f midnight NY time
  62
  63     std::cout << "\nUTC <--> New York while DST is NOT active (5 hours)"
  64               << std::endl;
  65     ptime t2 =  us_eastern::local_to_utc(t1);
  66     std::cout << to_simple_string(t1) << " in New York is "
  67               << to_simple_string(t2) << " UTC time "
  68               << std::endl;
  69
  70     ptime t3 = us_eastern::utc_to_local(t2);//back should be the same
  71     std::cout << to_simple_string(t2) << " UTC is "
  72               << to_simple_string(t3) << " New York time "
  73               << "\n\n";
  74
  75     ptime t4(date(2002,May,31), hours(20)); //4 hours b/f midnight NY time
  76     std::cout << "UTC <--> New York while DST is active (4 hours)" << std::endl;
  77     ptime t5 = us_eastern::local_to_utc(t4);
  78     std::cout << to_simple_string(t4) << " in New York is "
  79               << to_simple_string(t5) << " UTC time "
  80               << std::endl;
  81
  82     ptime t6 = us_eastern::utc_to_local(t5);//back should be the same
  83     std::cout << to_simple_string(t5) << " UTC is "
  84               << to_simple_string(t6) << " New York time "
  85               << "\n" << std::endl;
  86
  87
  88     //Arizona timezone is utc-7 with no dst
  89     typedef boost::date_time::local_adjustor<ptime, -7, no_dst> us_arizona;
  90
  91     ptime t7(date(2002,May,31), hours(17));
  92     std::cout << "UTC <--> Arizona (7 hours)" << std::endl;
  93     ptime t8 = us_arizona::local_to_utc(t7);
  94     std::cout << to_simple_string(t7) << " in Arizona is "
  95               << to_simple_string(t8) << " UTC time "
  96               << std::endl;
  97
  98     return 0;
  99   }
 100
 101     ]]>
 102   </programlisting>
 103 </section>