<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>async_write (4 of 4 overloads)</title> <link rel="stylesheet" href="../../../boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.75.2"> <link rel="home" href="../../../boost_asio.html" title="Boost.Asio"> <link rel="up" href="../async_write.html" title="async_write"> <link rel="prev" href="overload3.html" title="async_write (3 of 4 overloads)"> <link rel="next" href="../async_write_at.html" title="async_write_at"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> <table cellpadding="2" width="100%"><tr> <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../boost.png"></td> <td align="center"><a href="../../../../../index.html">Home</a></td> <td align="center"><a href="../../../../../libs/libraries.htm">Libraries</a></td> <td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> <td align="center"><a href="../../../../../more/index.htm">More</a></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="overload3.html"><img src="../../../../../doc/html/images/prev.png" alt="Prev"></a><a accesskey="u" href="../async_write.html"><img src="../../../../../doc/html/images/up.png" alt="Up"></a><a accesskey="h" href="../../../boost_asio.html"><img src="../../../../../doc/html/images/home.png" alt="Home"></a><a accesskey="n" href="../async_write_at.html"><img src="../../../../../doc/html/images/next.png" alt="Next"></a> </div> <div class="section" title="async_write (4 of 4 overloads)"> <div class="titlepage"><div><div><h4 class="title"> <a name="boost_asio.reference.async_write.overload4"></a><a class="link" href="overload4.html" title="async_write (4 of 4 overloads)"> async_write (4 of 4 overloads)</a> </h4></div></div></div> <p> Start an asynchronous operation to write a certain amount of data to a stream. </p> <pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <a class="link" href="../AsyncWriteStream.html" title="Buffer-oriented asynchronous write stream requirements">AsyncWriteStream</a><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Allocator</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">CompletionCondition</span><span class="special">,</span> <span class="keyword">typename</span> <a class="link" href="../WriteHandler.html" title="Write handler requirements">WriteHandler</a><span class="special">></span> <span class="keyword">void</span> <span class="identifier">async_write</span><span class="special">(</span> <span class="identifier">AsyncWriteStream</span> <span class="special">&</span> <span class="identifier">s</span><span class="special">,</span> <span class="identifier">basic_streambuf</span><span class="special"><</span> <span class="identifier">Allocator</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">b</span><span class="special">,</span> <span class="identifier">CompletionCondition</span> <span class="identifier">completion_condition</span><span class="special">,</span> <span class="identifier">WriteHandler</span> <span class="identifier">handler</span><span class="special">);</span> </pre> <p> This function is used to asynchronously write a certain number of bytes of data to a stream. The function call always returns immediately. The asynchronous operation will continue until one of the following conditions is true: </p> <div class="itemizedlist"><ul class="itemizedlist" type="disc"> <li class="listitem"> All of the data in the supplied basic_streambuf has been written. </li> <li class="listitem"> The completion_condition function object returns 0. </li> </ul></div> <p> This operation is implemented in terms of zero or more calls to the stream's async_write_some function. </p> <a name="boost_asio.reference.async_write.overload4.parameters"></a><h6> <a name="id678983"></a> <a class="link" href="overload4.html#boost_asio.reference.async_write.overload4.parameters">Parameters</a> </h6> <div class="variablelist"> <p class="title"><b></b></p> <dl> <dt><span class="term">s</span></dt> <dd><p> The stream to which the data is to be written. The type must support the AsyncWriteStream concept. </p></dd> <dt><span class="term">b</span></dt> <dd><p> A <a class="link" href="../basic_streambuf.html" title="basic_streambuf"><code class="computeroutput"><span class="identifier">basic_streambuf</span></code></a> object from which data will be written. Ownership of the streambuf is retained by the caller, which must guarantee that it remains valid until the handler is called. </p></dd> <dt><span class="term">completion_condition</span></dt> <dd> <p> The function object to be called to determine whether the write operation is complete. The signature of the function object must be: </p> <pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">completion_condition</span><span class="special">(</span> <span class="comment">// Result of latest async_write_some operation. </span> <span class="keyword">const</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">&</span> <span class="identifier">error</span><span class="special">,</span> <span class="comment">// Number of bytes transferred so far. </span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">bytes_transferred</span> <span class="special">);</span> </pre> <p> A return value of 0 indicates that the write operation is complete. A non-zero return value indicates the maximum number of bytes to be written on the next call to the stream's async_write_some function. </p> </dd> <dt><span class="term">handler</span></dt> <dd> <p> The handler to be called when the write operation completes. Copies will be made of the handler as required. The function signature of the handler must be: </p> <pre class="programlisting"><span class="keyword">void</span> <span class="identifier">handler</span><span class="special">(</span> <span class="keyword">const</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">&</span> <span class="identifier">error</span><span class="special">,</span> <span class="comment">// Result of operation. </span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">bytes_transferred</span> <span class="comment">// Number of bytes written from the </span> <span class="comment">// buffers. If an error occurred, </span> <span class="comment">// this will be less than the sum </span> <span class="comment">// of the buffer sizes. </span><span class="special">);</span> </pre> <p> Regardless of whether the asynchronous operation completes immediately or not, the handler will not be invoked from within this function. Invocation of the handler will be performed in a manner equivalent to using <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">io_service</span><span class="special">::</span><span class="identifier">post</span><span class="special">()</span></code>. </p> </dd> </dl> </div> </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="overload3.html"><img src="../../../../../doc/html/images/prev.png" alt="Prev"></a><a accesskey="u" href="../async_write.html"><img src="../../../../../doc/html/images/up.png" alt="Up"></a><a accesskey="h" href="../../../boost_asio.html"><img src="../../../../../doc/html/images/home.png" alt="Home"></a><a accesskey="n" href="../async_write_at.html"><img src="../../../../../doc/html/images/next.png" alt="Next"></a> </div> </body> </html>