1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>write_at (7 of 8 overloads)</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="../write_at.html" title="write_at"> 9<link rel="prev" href="overload6.html" title="write_at (6 of 8 overloads)"> 10<link rel="next" href="overload8.html" title="write_at (8 of 8 overloads)"> 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="overload6.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../write_at.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="overload8.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h4 class="title"> 27<a name="boost_asio.reference.write_at.overload7"></a><a class="link" href="overload7.html" title="write_at (7 of 8 overloads)">write_at (7 28 of 8 overloads)</a> 29</h4></div></div></div> 30<p> 31 Write a certain amount of data at a specified offset before returning. 32 </p> 33<pre class="programlisting">template< 34 typename <a class="link" href="../SyncRandomAccessWriteDevice.html" title="Buffer-oriented synchronous random-access write device requirements">SyncRandomAccessWriteDevice</a>, 35 typename Allocator, 36 typename <a class="link" href="../CompletionCondition.html" title="Completion condition requirements">CompletionCondition</a>> 37std::size_t write_at( 38 SyncRandomAccessWriteDevice & d, 39 uint64_t offset, 40 basic_streambuf< Allocator > & b, 41 CompletionCondition completion_condition); 42</pre> 43<p> 44 This function is used to write a certain number of bytes of data to a random 45 access device at a specified offset. The call will block until one of the 46 following conditions is true: 47 </p> 48<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 49<li class="listitem"> 50 All of the data in the supplied <a class="link" href="../basic_streambuf.html" title="basic_streambuf"><code class="computeroutput">basic_streambuf</code></a> 51 has been written. 52 </li> 53<li class="listitem"> 54 The completion_condition function object returns 0. 55 </li> 56</ul></div> 57<p> 58 This operation is implemented in terms of zero or more calls to the device's 59 write_some_at function. 60 </p> 61<h6> 62<a name="boost_asio.reference.write_at.overload7.h0"></a> 63 <span class="phrase"><a name="boost_asio.reference.write_at.overload7.parameters"></a></span><a class="link" href="overload7.html#boost_asio.reference.write_at.overload7.parameters">Parameters</a> 64 </h6> 65<div class="variablelist"> 66<p class="title"><b></b></p> 67<dl class="variablelist"> 68<dt><span class="term">d</span></dt> 69<dd><p> 70 The device to which the data is to be written. The type must support 71 the SyncRandomAccessWriteDevice concept. 72 </p></dd> 73<dt><span class="term">offset</span></dt> 74<dd><p> 75 The offset at which the data will be written. 76 </p></dd> 77<dt><span class="term">b</span></dt> 78<dd><p> 79 The <a class="link" href="../basic_streambuf.html" title="basic_streambuf"><code class="computeroutput">basic_streambuf</code></a> 80 object from which data will be written. 81 </p></dd> 82<dt><span class="term">completion_condition</span></dt> 83<dd> 84<p> 85 The function object to be called to determine whether the write operation 86 is complete. The signature of the function object must be: 87</p> 88<pre class="programlisting">std::size_t completion_condition( 89 // Result of latest write_some_at operation. 90 const boost::system::error_code& error, 91 92 // Number of bytes transferred so far. 93 std::size_t bytes_transferred 94); 95</pre> 96<p> 97 A return value of 0 indicates that the write operation is complete. 98 A non-zero return value indicates the maximum number of bytes to 99 be written on the next call to the device's write_some_at function. 100 </p> 101</dd> 102</dl> 103</div> 104<h6> 105<a name="boost_asio.reference.write_at.overload7.h1"></a> 106 <span class="phrase"><a name="boost_asio.reference.write_at.overload7.return_value"></a></span><a class="link" href="overload7.html#boost_asio.reference.write_at.overload7.return_value">Return Value</a> 107 </h6> 108<p> 109 The number of bytes transferred. 110 </p> 111<h6> 112<a name="boost_asio.reference.write_at.overload7.h2"></a> 113 <span class="phrase"><a name="boost_asio.reference.write_at.overload7.exceptions"></a></span><a class="link" href="overload7.html#boost_asio.reference.write_at.overload7.exceptions">Exceptions</a> 114 </h6> 115<div class="variablelist"> 116<p class="title"><b></b></p> 117<dl class="variablelist"> 118<dt><span class="term">boost::system::system_error</span></dt> 119<dd><p> 120 Thrown on failure. 121 </p></dd> 122</dl> 123</div> 124</div> 125<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 126<td align="left"></td> 127<td align="right"><div class="copyright-footer">Copyright © 2003-2020 Christopher M. 128 Kohlhoff<p> 129 Distributed under the Boost Software License, Version 1.0. (See accompanying 130 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>) 131 </p> 132</div></td> 133</tr></table> 134<hr> 135<div class="spirit-nav"> 136<a accesskey="p" href="overload6.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../write_at.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="overload8.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> 137</div> 138</body> 139</html> 140
