1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Time traits requirements</title> 5<link rel="stylesheet" href="../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../boost_asio.html" title="Boost.Asio"> 8<link rel="up" href="../reference.html" title="Reference"> 9<link rel="prev" href="SyncWriteStream.html" title="Buffer-oriented synchronous write stream requirements"> 10<link rel="next" href="WaitHandler.html" title="Wait handler requirements"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../boost.png"></td> 15<td align="center"><a href="../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="SyncWriteStream.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../reference.html"><img src="../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../boost_asio.html"><img src="../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="WaitHandler.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h3 class="title"> 27<a name="boost_asio.reference.TimeTraits"></a><a class="link" href="TimeTraits.html" title="Time traits requirements">Time traits requirements</a> 28</h3></div></div></div> 29<p> 30 In the table below, <code class="computeroutput">X</code> denotes a time traits class for time type 31 <code class="computeroutput">Time</code>, <code class="computeroutput">t</code>, <code class="computeroutput">t1</code>, and <code class="computeroutput">t2</code> denote 32 values of type <code class="computeroutput">Time</code>, and <code class="computeroutput">d</code> denotes a value of type 33 <code class="computeroutput">X::duration_type</code>. 34 </p> 35<div class="table"> 36<a name="boost_asio.reference.TimeTraits.t0"></a><p class="title"><b>Table 32. TimeTraits requirements</b></p> 37<div class="table-contents"><table class="table" summary="TimeTraits requirements"> 38<colgroup> 39<col> 40<col> 41<col> 42</colgroup> 43<thead><tr> 44<th> 45 <p> 46 expression 47 </p> 48 </th> 49<th> 50 <p> 51 return type 52 </p> 53 </th> 54<th> 55 <p> 56 assertion/note<br> pre/post-condition 57 </p> 58 </th> 59</tr></thead> 60<tbody> 61<tr> 62<td> 63 <p> 64 <code class="computeroutput">X::time_type</code> 65 </p> 66 </td> 67<td> 68 <p> 69 <code class="computeroutput">Time</code> 70 </p> 71 </td> 72<td> 73 <p> 74 Represents an absolute time. Must support default construction, 75 and meet the requirements for <code class="computeroutput">CopyConstructible</code> and 76 <code class="computeroutput">Assignable</code>. 77 </p> 78 </td> 79</tr> 80<tr> 81<td> 82 <p> 83 <code class="computeroutput">X::duration_type</code> 84 </p> 85 </td> 86<td> 87 </td> 88<td> 89 <p> 90 Represents the difference between two absolute times. Must support 91 default construction, and meet the requirements for <code class="computeroutput">CopyConstructible</code> 92 and <code class="computeroutput">Assignable</code>. A duration can be positive, negative, 93 or zero. 94 </p> 95 </td> 96</tr> 97<tr> 98<td> 99 <p> 100 <code class="computeroutput">X::now();</code> 101 </p> 102 </td> 103<td> 104 <p> 105 <code class="computeroutput">time_type</code> 106 </p> 107 </td> 108<td> 109 <p> 110 Returns the current time. 111 </p> 112 </td> 113</tr> 114<tr> 115<td> 116 <p> 117 <code class="computeroutput">X::add(t, d);</code> 118 </p> 119 </td> 120<td> 121 <p> 122 <code class="computeroutput">time_type</code> 123 </p> 124 </td> 125<td> 126 <p> 127 Returns a new absolute time resulting from adding the duration 128 <code class="computeroutput">d</code> to the absolute time <code class="computeroutput">t</code>. 129 </p> 130 </td> 131</tr> 132<tr> 133<td> 134 <p> 135 <code class="computeroutput">X::subtract(t1, t2);</code> 136 </p> 137 </td> 138<td> 139 <p> 140 <code class="computeroutput">duration_type</code> 141 </p> 142 </td> 143<td> 144 <p> 145 Returns the duration resulting from subtracting <code class="computeroutput">t2</code> 146 from <code class="computeroutput">t1</code>. 147 </p> 148 </td> 149</tr> 150<tr> 151<td> 152 <p> 153 <code class="computeroutput">X::less_than(t1, t2);</code> 154 </p> 155 </td> 156<td> 157 <p> 158 <code class="computeroutput">bool</code> 159 </p> 160 </td> 161<td> 162 <p> 163 Returns whether <code class="computeroutput">t1</code> is to be treated as less than 164 <code class="computeroutput">t2</code>. 165 </p> 166 </td> 167</tr> 168<tr> 169<td> 170 <p> 171 <code class="computeroutput">X::to_posix_duration(d);</code> 172 </p> 173 </td> 174<td> 175 <p> 176 <code class="computeroutput">date_time::time_duration_type</code> 177 </p> 178 </td> 179<td> 180 <p> 181 Returns the <code class="computeroutput">date_time::time_duration_type</code> value that 182 most closely represents the duration <code class="computeroutput">d</code>. 183 </p> 184 </td> 185</tr> 186</tbody> 187</table></div> 188</div> 189<br class="table-break"> 190</div> 191<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 192<td align="left"></td> 193<td align="right"><div class="copyright-footer">Copyright © 2003-2020 Christopher M. 194 Kohlhoff<p> 195 Distributed under the Boost Software License, Version 1.0. (See accompanying 196 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>) 197 </p> 198</div></td> 199</tr></table> 200<hr> 201<div class="spirit-nav"> 202<a accesskey="p" href="SyncWriteStream.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../reference.html"><img src="../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../boost_asio.html"><img src="../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="WaitHandler.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 203</div> 204</body> 205</html> 206
