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  28 <a name="date_time.examples.general_usage_examples"></a>General Usage Examples</h2></div></div></div>
  29 <p>
  30     The following provides some sample usage of dates.
  31     See <a class="link" href="../gregorian.html" title="Gregorian">Date Programming</a>
  32     for more details.
  33
  34     </p>
  35 <pre class="programlisting"><span class="keyword">using namespace</span> boost::gregorian;
  36     date weekstart(<span class="number">2002</span>,Feb,<span class="number">1</span>);
  37     date weekend  = weekstart + weeks(<span class="number">1</span>);
  38     date d2 = d1 + days(<span class="number">5</span>);
  39     date today = day_clock::local_day();
  40     if (d2 &gt;= today) {} <span class="comment">//date comparison operators</span>
  41
  42     date_period thisWeek(d1,d2);
  43     <span class="keyword">if</span> (thisWeek.contains(today)) {}<span class="comment">//do something
  44
  45     //iterate and print the week</span>
  46     day_iterator itr(weekstart);
  47     <span class="keyword">while</span> (itr &lt;= weekend) {
  48      std::cout &lt;&lt; (*itr) &lt;&lt; std::endl;
  49      ++itr;
  50     }
  51     <span class="comment">//input streaming</span>
  52     std::stringstream ss(<span class="string">"2004-Jan-1"</span>);
  53     ss &gt;&gt; d3;
  54
  55     <span class="comment">//date generator functions</span>
  56     date d5 = next_weekday(d4, Sunday); <span class="comment">//calculate Sunday following d4
  57
  58     //US labor day is first Monday in Sept</span>
  59         <span class="keyword">typedef</span> nth_day_of_the_week_in_month nth_dow;
  60     nth_dow labor_day(nth_dow::first,Monday, Sep);
  61     <span class="comment">//calculate a specific date for 2004 from functor</span>
  62     date d6 = labor_day.get_date(<span class="number">2004</span>);
  63     </pre>
  64 <p>
  65
  66       The following provides some example code using times.
  67       See <a class="link" href="../posix_time.html" title="Posix Time">Time Programming</a>
  68       for more details.
  69
  70     </p>
  71 <pre class="programlisting"><span class="keyword">using namespace</span> boost::posix_time;
  72     date d(<span class="number">2002</span>,Feb,<span class="number">1</span>); <span class="comment">//an arbitrary date</span>
  73     ptime t1(d, hours(<span class="number">5</span>)+nanosec(<span class="number">100</span>)); <span class="comment">//date + time of day offset</span>
  74     ptime t2 = t1 - minutes(<span class="number">4</span>)+seconds(<span class="number">2</span>);
  75     ptime now = second_clock::local_time(); <span class="comment">//use the clock</span>
  76     date today = now.date(); <span class="comment">//Get the date part out of the time</span>
  77     date tomorrow = today + date_duration(<span class="number">1</span>);
  78     ptime tomorrow_start(tomorrow); <span class="comment">//midnight
  79
  80     //input streaming</span>
  81     std::stringstream ss(<span class="string">"2004-Jan-1 05:21:33.20"</span>);
  82     ss &gt;&gt; t2;
  83
  84     <span class="comment">//starting at current time iterator adds by one hour</span>
  85     time_iterator titr(now,hours(<span class="number">1</span>));
  86     <span class="keyword">for</span> (; titr &lt; tomorrow_start; ++titr) {
  87      std::cout &lt;&lt; (*titr) &lt;&lt; std::endl;
  88     }
  89     </pre>
  90 <p>
  91   </p>
  92 <p>
  93       The following provides some example code using times.
  94       See <a class="link" href="../local_time.html" title="Local Time">Local Time Programming</a>
  95       for more details.
  96
  97     </p>
  98 <pre class="programlisting">
  99     <span class="keyword">using namespace</span> boost::local_time;
 100     <span class="comment">//setup some timezones for creating and adjusting times
 101     //first time zone uses the time zone file for regional timezone definitions</span>
 102     tz_database tz_db;
 103     tz_db.load_from_file(<span class="string">"date_time_zonespec.csv"</span>);
 104     time_zone_ptr nyc_tz = tz_db.time_zone_from_region(<span class="string">"America/New_York"</span>);
 105     <span class="comment">//This timezone uses a posix time zone string definition to create a time zone</span>
 106     time_zone_ptr phx_tz(new posix_time_zone(<span class="string">"MST-07:00:00"</span>));
 107
 108     <span class="comment">//local departure time in phoenix is 11 pm on April 2 2005
 109     // Note that New York changes to daylight savings on Apr 3 at 2 am)</span>
 110     local_date_time phx_departure(date(<span class="number">2005</span>, Apr, <span class="number">2</span>), hours(<span class="number">23</span>), phx_tz,
 111                                   local_date_time::NOT_DATE_TIME_ON_ERROR);
 112
 113     time_duration flight_length = hours(<span class="number">4</span>) + minutes(<span class="number">30</span>);
 114     local_date_time phx_arrival = phx_departure + flight_length;
 115     <span class="comment">//convert the phx time to a nyz time</span>
 116     local_date_time nyc_arrival = phx_arrival.local_time_in(nyc_tz);
 117
 118     <span class="comment">//2005-Apr-03 06:30:00 EDT</span>
 119     std::cout &lt;&lt; nyc_arrival &lt;&lt; std::endl;
 120     </pre>
 121 <p>
 122   </p>
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