1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Requirements on read and write operations</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="asynchronous_operations.html" title="Requirements on asynchronous operations"> 10<link rel="next" href="synchronous_socket_operations.html" title="Requirements on synchronous socket operations"> 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="asynchronous_operations.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="synchronous_socket_operations.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.read_write_operations"></a><a class="link" href="read_write_operations.html" title="Requirements on read and write operations">Requirements 28 on read and write operations</a> 29</h3></div></div></div> 30<p> 31 A <span class="emphasis"><em>read operation</em></span> is an operation that reads data into 32 a mutable buffer sequence argument of a type meeting <a class="link" href="MutableBufferSequence.html" title="Mutable buffer sequence requirements"><code class="computeroutput">MutableBufferSequence</code></a> 33 requirements. The mutable buffer sequence specifies memory where the data 34 should be placed. A read operation shall always fill a buffer in the sequence 35 completely before proceeding to the next. 36 </p> 37<p> 38 A <span class="emphasis"><em>write operation</em></span> is an operation that writes data from 39 a constant buffer sequence argument of a type meeting <a class="link" href="ConstBufferSequence.html" title="Constant buffer sequence requirements"><code class="computeroutput">ConstBufferSequence</code></a> 40 requirements. The constant buffer sequence specifies memory where the data 41 to be written is located. A write operation shall always write a buffer in 42 the sequence completely before proceeding to the next. 43 </p> 44<p> 45 If a read or write operation is also an <a class="link" href="asynchronous_operations.html" title="Requirements on asynchronous operations">asynchronous 46 operation</a>, the operation shall maintain one or more copies of the 47 buffer sequence until such time as the operation no longer requires access 48 to the memory specified by the buffers in the sequence. The program shall 49 ensure the memory remains valid until: 50 </p> 51<p> 52 — the last copy of the buffer sequence is destroyed, or 53 </p> 54<p> 55 — the completion handler for the asynchronous operation is invoked, 56 </p> 57<p> 58 whichever comes first. 59 </p> 60</div> 61<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 62<td align="left"></td> 63<td align="right"><div class="copyright-footer">Copyright © 2003-2020 Christopher M. 64 Kohlhoff<p> 65 Distributed under the Boost Software License, Version 1.0. (See accompanying 66 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>) 67 </p> 68</div></td> 69</tr></table> 70<hr> 71<div class="spirit-nav"> 72<a accesskey="p" href="asynchronous_operations.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="synchronous_socket_operations.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 73</div> 74</body> 75</html> 76
