1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>write_at (2 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="overload1.html" title="write_at (1 of 8 overloads)"> 10<link rel="next" href="overload3.html" title="write_at (3 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="overload1.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="overload3.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.overload2"></a><a class="link" href="overload2.html" title="write_at (2 of 8 overloads)">write_at (2 28 of 8 overloads)</a> 29</h4></div></div></div> 30<p> 31 Write all of the supplied data at the 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 <a class="link" href="../ConstBufferSequence.html" title="Constant buffer sequence requirements">ConstBufferSequence</a>> 36std::size_t write_at( 37 SyncRandomAccessWriteDevice & d, 38 uint64_t offset, 39 const ConstBufferSequence & buffers, 40 boost::system::error_code & ec); 41</pre> 42<p> 43 This function is used to write a certain number of bytes of data to a random 44 access device at a specified offset. The call will block until one of the 45 following conditions is true: 46 </p> 47<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 48<li class="listitem"> 49 All of the data in the supplied buffers has been written. That is, 50 the bytes transferred is equal to the sum of the buffer sizes. 51 </li> 52<li class="listitem"> 53 An error occurred. 54 </li> 55</ul></div> 56<p> 57 This operation is implemented in terms of zero or more calls to the device's 58 write_some_at function. 59 </p> 60<h6> 61<a name="boost_asio.reference.write_at.overload2.h0"></a> 62 <span class="phrase"><a name="boost_asio.reference.write_at.overload2.parameters"></a></span><a class="link" href="overload2.html#boost_asio.reference.write_at.overload2.parameters">Parameters</a> 63 </h6> 64<div class="variablelist"> 65<p class="title"><b></b></p> 66<dl class="variablelist"> 67<dt><span class="term">d</span></dt> 68<dd><p> 69 The device to which the data is to be written. The type must support 70 the SyncRandomAccessWriteDevice concept. 71 </p></dd> 72<dt><span class="term">offset</span></dt> 73<dd><p> 74 The offset at which the data will be written. 75 </p></dd> 76<dt><span class="term">buffers</span></dt> 77<dd><p> 78 One or more buffers containing the data to be written. The sum of 79 the buffer sizes indicates the maximum number of bytes to write to 80 the device. 81 </p></dd> 82<dt><span class="term">ec</span></dt> 83<dd><p> 84 Set to indicate what error occurred, if any. 85 </p></dd> 86</dl> 87</div> 88<h6> 89<a name="boost_asio.reference.write_at.overload2.h1"></a> 90 <span class="phrase"><a name="boost_asio.reference.write_at.overload2.return_value"></a></span><a class="link" href="overload2.html#boost_asio.reference.write_at.overload2.return_value">Return Value</a> 91 </h6> 92<p> 93 The number of bytes transferred. 94 </p> 95<h6> 96<a name="boost_asio.reference.write_at.overload2.h2"></a> 97 <span class="phrase"><a name="boost_asio.reference.write_at.overload2.example"></a></span><a class="link" href="overload2.html#boost_asio.reference.write_at.overload2.example">Example</a> 98 </h6> 99<p> 100 To write a single data buffer use the <a class="link" href="../buffer.html" title="buffer"><code class="computeroutput">buffer</code></a> 101 function as follows: 102 </p> 103<pre class="programlisting">boost::asio::write_at(d, 42, 104 boost::asio::buffer(data, size), ec); 105</pre> 106<p> 107 See the <a class="link" href="../buffer.html" title="buffer"><code class="computeroutput">buffer</code></a> 108 documentation for information on writing multiple buffers in one go, and 109 how to use it with arrays, boost::array or std::vector. 110 </p> 111<h6> 112<a name="boost_asio.reference.write_at.overload2.h3"></a> 113 <span class="phrase"><a name="boost_asio.reference.write_at.overload2.remarks"></a></span><a class="link" href="overload2.html#boost_asio.reference.write_at.overload2.remarks">Remarks</a> 114 </h6> 115<p> 116 This overload is equivalent to calling: 117 </p> 118<pre class="programlisting">boost::asio::write_at( 119 d, offset, buffers, 120 boost::asio::transfer_all(), ec); 121</pre> 122</div> 123<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 124<td align="left"></td> 125<td align="right"><div class="copyright-footer">Copyright © 2003-2020 Christopher M. 126 Kohlhoff<p> 127 Distributed under the Boost Software License, Version 1.0. (See accompanying 128 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>) 129 </p> 130</div></td> 131</tr></table> 132<hr> 133<div class="spirit-nav"> 134<a accesskey="p" href="overload1.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="overload3.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> 135</div> 136</body> 137</html> 138
