<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>Time traits requirements</title> <link rel="stylesheet" href="../../boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.73.2"> <link rel="start" href="../../index.html" title="Asio"> <link rel="up" href="../reference.html" title="Reference"> <link rel="prev" href="SyncWriteStream.html" title="Buffer-oriented synchronous write stream requirements"> <link rel="next" href="TimerService.html" title="Timer service requirements"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> <table cellpadding="2" width="100%"><tr><td valign="top"><img alt="asio C++ library" width="250" height="60" src="../../asio.png"></td></tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="SyncWriteStream.html"><img src="../../prev.png" alt="Prev"></a><a accesskey="u" href="../reference.html"><img src="../../up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../home.png" alt="Home"></a><a accesskey="n" href="TimerService.html"><img src="../../next.png" alt="Next"></a> </div> <div class="section" lang="en"> <div class="titlepage"><div><div><h3 class="title"> <a name="asio.reference.TimeTraits"></a><a class="link" href="TimeTraits.html" title="Time traits requirements"> Time traits requirements</a> </h3></div></div></div> <p> In the table below, <code class="computeroutput"><span class="identifier">X</span></code> denotes a time traits class for time type <code class="computeroutput"><span class="identifier">Time</span></code>, <code class="computeroutput"><span class="identifier">t</span></code>, <code class="computeroutput"><span class="identifier">t1</span></code>, and <code class="computeroutput"><span class="identifier">t2</span></code> denote values of type <code class="computeroutput"><span class="identifier">Time</span></code>, and <code class="computeroutput"><span class="identifier">d</span></code> denotes a value of type <code class="computeroutput"><span class="identifier">X</span><span class="special">::</span><span class="identifier">duration_type</span></code>. </p> <div class="table"> <a name="id573946"></a><p class="title"><b>Table 35. TimeTraits requirements</b></p> <div class="table-contents"><table class="table" summary="TimeTraits requirements"> <colgroup> <col> <col> <col> </colgroup> <thead><tr> <th> <p> expression </p> </th> <th> <p> return type </p> </th> <th> <p> assertion/note<br> pre/post-condition </p> </th> </tr></thead> <tbody> <tr> <td> <p> <code class="computeroutput"><span class="identifier">X</span><span class="special">::</span><span class="identifier">time_type</span></code> </p> </td> <td> <p> <code class="computeroutput"><span class="identifier">Time</span></code> </p> </td> <td> <p> Represents an absolute time. Must support default construction, and meet the requirements for <code class="computeroutput"><span class="identifier">CopyConstructible</span></code> and <code class="computeroutput"><span class="identifier">Assignable</span></code>. </p> </td> </tr> <tr> <td> <p> <code class="computeroutput"><span class="identifier">X</span><span class="special">::</span><span class="identifier">duration_type</span></code> </p> </td> <td> <p> </p> </td> <td> <p> Represents the difference between two absolute times. Must support default construction, and meet the requirements for <code class="computeroutput"><span class="identifier">CopyConstructible</span></code> and <code class="computeroutput"><span class="identifier">Assignable</span></code>. A duration can be positive, negative, or zero. </p> </td> </tr> <tr> <td> <p> <code class="computeroutput"><span class="identifier">X</span><span class="special">::</span><span class="identifier">now</span><span class="special">();</span></code> </p> </td> <td> <p> <code class="computeroutput"><span class="identifier">time_type</span></code> </p> </td> <td> <p> Returns the current time. </p> </td> </tr> <tr> <td> <p> <code class="computeroutput"><span class="identifier">X</span><span class="special">::</span><span class="identifier">add</span><span class="special">(</span><span class="identifier">t</span><span class="special">,</span> <span class="identifier">d</span><span class="special">);</span></code> </p> </td> <td> <p> <code class="computeroutput"><span class="identifier">time_type</span></code> </p> </td> <td> <p> Returns a new absolute time resulting from adding the duration <code class="computeroutput"><span class="identifier">d</span></code> to the absolute time <code class="computeroutput"><span class="identifier">t</span></code>. </p> </td> </tr> <tr> <td> <p> <code class="computeroutput"><span class="identifier">X</span><span class="special">::</span><span class="identifier">subtract</span><span class="special">(</span><span class="identifier">t1</span><span class="special">,</span> <span class="identifier">t2</span><span class="special">);</span></code> </p> </td> <td> <p> <code class="computeroutput"><span class="identifier">duration_type</span></code> </p> </td> <td> <p> Returns the duration resulting from subtracting <code class="computeroutput"><span class="identifier">t2</span></code> from <code class="computeroutput"><span class="identifier">t1</span></code>. </p> </td> </tr> <tr> <td> <p> <code class="computeroutput"><span class="identifier">X</span><span class="special">::</span><span class="identifier">less_than</span><span class="special">(</span><span class="identifier">t1</span><span class="special">,</span> <span class="identifier">t2</span><span class="special">);</span></code> </p> </td> <td> <p> <code class="computeroutput"><span class="keyword">bool</span></code> </p> </td> <td> <p> Returns whether <code class="computeroutput"><span class="identifier">t1</span></code> is to be treated as less than <code class="computeroutput"><span class="identifier">t2</span></code>. </p> </td> </tr> <tr> <td> <p> <code class="computeroutput"><span class="identifier">X</span><span class="special">::</span><span class="identifier">to_posix_duration</span><span class="special">(</span><span class="identifier">d</span><span class="special">);</span></code> </p> </td> <td> <p> <code class="computeroutput"><span class="identifier">date_time</span><span class="special">::</span><span class="identifier">time_duration_type</span></code> </p> </td> <td> <p> Returns the <code class="computeroutput"><span class="identifier">date_time</span><span class="special">::</span><span class="identifier">time_duration_type</span></code> value that most closely represents the duration <code class="computeroutput"><span class="identifier">d</span></code>. </p> </td> </tr> </tbody> </table></div> </div> <br class="table-break"> </div> <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> <td align="left"></td> <td align="right"><div class="copyright-footer">Copyright © 2003 - 2010 Christopher M. Kohlhoff<p> Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) </p> </div></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="SyncWriteStream.html"><img src="../../prev.png" alt="Prev"></a><a accesskey="u" href="../reference.html"><img src="../../up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../home.png" alt="Home"></a><a accesskey="n" href="TimerService.html"><img src="../../next.png" alt="Next"></a> </div> </body> </html>