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<h1>posix_time::time_iterator</h1>
<p> <p>
<hr>
<a href="index.html">Overall Index</a> --
<a href="gregorian.html">Gregorian Index</a> --
<a href="posix_time.html">Posix Time Index</a>
<p>
<font class="bold">Time Iterators</font>
<p>
<a href="#intro">Introduction</a> --
<a href="#header">Header</a> --
<a href="#classoverview">Class Overview</a> --
<a href="#operators">Operators</a>
<p>
<h2><a name="intro">Introduction</a></h2>
<p>
Time iterators provide a mechanism for iteration through times. Time iterators are similar to <a href="http://www.sgi.com/tech/stl/BidirectionalIterator.html">Bidirectional Iterators</a>.
However, time_iterators are different than standard iterators in that there is no underlying sequence, just a calculation function. In addition, time_iterators are directly comparable against instances of <a href="class_ptime.html">class ptime</a>. Thus a second iterator for the end point of the iteration is not required, but rather a point in time can be used directly. For example, the following code iterates using a 15 minute iteration interval. The <a href="exp-print_hours.html">print hours</a> example also illustrates the use of the time_iterator.
<p>
<div class="fragment">
<pre>
<font class="preprocessor">#include "boost/date_time/posix_time/posix_time.hpp"</font>
<font class="preprocessor">#include <iostream></font>
<font class="keywordtype">int</font>
<a name="a0"></a><a class="code" href="time__iter_8cpp.html#a0">main</a>()
{
<font class="keyword">using</font> <font class="keyword">namespace </font>boost::gregorian;
<font class="keyword">using</font> <font class="keyword">namespace </font>boost::posix_time;
date d(2000,Jan,20);
ptime start(d);
ptime end = start + hours(1);
time_iterator titr(start,minutes(15)); <font class="comment">//increment by 15 minutes</font>
<font class="comment">//produces 00:00:00, 00:15:00, 00:30:00, 00:45:00</font>
<font class="keywordflow">while</font> (titr < end) {
std::cout << to_simple_string(*titr) << std::endl;
++titr;
}
std::cout << <font class="stringliteral">"Now backward"</font> << std::endl;
<font class="comment">//produces 01:00:00, 00:45:00, 00:30:00, 00:15:00</font>
<font class="keywordflow">while</font> (titr > start) {
std::cout << to_simple_string(*titr) << std::endl;
--titr;
}
}
</pre>
</div>
<p>
<p>
<h2><a name="header">Header</a></h2>
<pre>
#include "boost/date_time/posix_time/posix_time.hpp" //include all types plus i/o
or
#include "boost/date_time/posix_time/posix_time_types.hpp" //no i/o just types
</pre>
<p>
<h2><a name="classoverview">Class Overview</a></h2>
<p>
<table border=1 cellspacing=3 cellpadding=3>
<tr><td><b>Class</b></td>
<td><b>Construction Parameters</b></td>
<td><b>Description</b></td></tr>
<tr><td>time_iterator</td>
<td>ptime start_time, time_duration increment</td>
<td>Iterate incrementing by the specified duration.</td></tr>
</table>
<p>
<h2><a name="operators">Operators</a></h2>
<p>
<table border=1 cellspacing=3 cellpadding=3>
<tr><td><b>Syntax</b></td><td><b>Description</b></td><td><b>Example</b></td></tr>
<tr><td class="nowrap">operator==(const ptime& rhs),
<br> operator!=(const ptime& rhs),
<br> operator>, operator<
<br> operator>=, operator<=</td>
<td>A full complement of comparison operators</td>
<td class="nowrap">date d(2002,Jan,1);<br>
ptime start_time(d, hours(1));<br>
//increment by 10 minutes<br>
time_iterator titr(start_time, minutes(10));<br>
ptime end_time = start_time + hours(2);<br>
if (titr == end_time) // false<br>
if (titr != end_time) // true<br>
if (titr >= end_time) // false<br>
if (titr <= end_time) // true<br>
</td></tr>
<tr><td><font class="func">prefix increment</font></td>
<td>Increment the iterator by the specified duration.</td>
<td class="nowrap">
//increment by 10 milli seconds<br>
time_iterator titr(start_time, milliseconds(10));<br>
++titr; // == start_time + 10 milliseconds
</td></tr>
<tr><td><font class="func">prefix decrement</font></td>
<td>Decrement the iterator by the specified time duration.</td>
<td class="nowrap">Example
time_iterator titr(start_time, time_duration(1,2,3)); <br>
--titr; // == start_time - 1 hour, 2 minutes, and 3 seconds
</td></tr>
</table>
<p>
<hr><address><small>
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Last modified: Sun Nov 2 20:02:29 MST 2003
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by <a href="mailto:jeff@crystalclearsoftware.com">Jeff Garland</a> © 2000-2003
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