1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>read (1 of 16 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="../read.html" title="read"> 9<link rel="prev" href="../read.html" title="read"> 10<link rel="next" href="overload2.html" title="read (2 of 16 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="../read.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../read.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="overload2.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.read.overload1"></a><a class="link" href="overload1.html" title="read (1 of 16 overloads)">read (1 of 16 28 overloads)</a> 29</h4></div></div></div> 30<p> 31 Attempt to read a certain amount of data from a stream before returning. 32 </p> 33<pre class="programlisting">template< 34 typename <a class="link" href="../SyncReadStream.html" title="Buffer-oriented synchronous read stream requirements">SyncReadStream</a>, 35 typename <a class="link" href="../MutableBufferSequence.html" title="Mutable buffer sequence requirements">MutableBufferSequence</a>> 36std::size_t read( 37 SyncReadStream & s, 38 const MutableBufferSequence & buffers, 39 typename enable_if< is_mutable_buffer_sequence< MutableBufferSequence >::value >::type * = 0); 40</pre> 41<p> 42 This function is used to read a certain number of bytes of data from a 43 stream. The call will block until one of the following conditions is true: 44 </p> 45<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 46<li class="listitem"> 47 The supplied buffers are full. That is, the bytes transferred is equal 48 to the sum of the buffer sizes. 49 </li> 50<li class="listitem"> 51 An error occurred. 52 </li> 53</ul></div> 54<p> 55 This operation is implemented in terms of zero or more calls to the stream's 56 read_some function. 57 </p> 58<h6> 59<a name="boost_asio.reference.read.overload1.h0"></a> 60 <span class="phrase"><a name="boost_asio.reference.read.overload1.parameters"></a></span><a class="link" href="overload1.html#boost_asio.reference.read.overload1.parameters">Parameters</a> 61 </h6> 62<div class="variablelist"> 63<p class="title"><b></b></p> 64<dl class="variablelist"> 65<dt><span class="term">s</span></dt> 66<dd><p> 67 The stream from which the data is to be read. The type must support 68 the SyncReadStream concept. 69 </p></dd> 70<dt><span class="term">buffers</span></dt> 71<dd><p> 72 One or more buffers into which the data will be read. The sum of 73 the buffer sizes indicates the maximum number of bytes to read from 74 the stream. 75 </p></dd> 76</dl> 77</div> 78<h6> 79<a name="boost_asio.reference.read.overload1.h1"></a> 80 <span class="phrase"><a name="boost_asio.reference.read.overload1.return_value"></a></span><a class="link" href="overload1.html#boost_asio.reference.read.overload1.return_value">Return 81 Value</a> 82 </h6> 83<p> 84 The number of bytes transferred. 85 </p> 86<h6> 87<a name="boost_asio.reference.read.overload1.h2"></a> 88 <span class="phrase"><a name="boost_asio.reference.read.overload1.exceptions"></a></span><a class="link" href="overload1.html#boost_asio.reference.read.overload1.exceptions">Exceptions</a> 89 </h6> 90<div class="variablelist"> 91<p class="title"><b></b></p> 92<dl class="variablelist"> 93<dt><span class="term">boost::system::system_error</span></dt> 94<dd><p> 95 Thrown on failure. 96 </p></dd> 97</dl> 98</div> 99<h6> 100<a name="boost_asio.reference.read.overload1.h3"></a> 101 <span class="phrase"><a name="boost_asio.reference.read.overload1.example"></a></span><a class="link" href="overload1.html#boost_asio.reference.read.overload1.example">Example</a> 102 </h6> 103<p> 104 To read into a single data buffer use the <a class="link" href="../buffer.html" title="buffer"><code class="computeroutput">buffer</code></a> 105 function as follows: 106 </p> 107<pre class="programlisting">boost::asio::read(s, boost::asio::buffer(data, size)); 108</pre> 109<p> 110 See the <a class="link" href="../buffer.html" title="buffer"><code class="computeroutput">buffer</code></a> 111 documentation for information on reading into multiple buffers in one go, 112 and how to use it with arrays, boost::array or std::vector. 113 </p> 114<h6> 115<a name="boost_asio.reference.read.overload1.h4"></a> 116 <span class="phrase"><a name="boost_asio.reference.read.overload1.remarks"></a></span><a class="link" href="overload1.html#boost_asio.reference.read.overload1.remarks">Remarks</a> 117 </h6> 118<p> 119 This overload is equivalent to calling: 120 </p> 121<pre class="programlisting">boost::asio::read( 122 s, buffers, 123 boost::asio::transfer_all()); 124</pre> 125</div> 126<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 127<td align="left"></td> 128<td align="right"><div class="copyright-footer">Copyright © 2003-2020 Christopher M. 129 Kohlhoff<p> 130 Distributed under the Boost Software License, Version 1.0. (See accompanying 131 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>) 132 </p> 133</div></td> 134</tr></table> 135<hr> 136<div class="spirit-nav"> 137<a accesskey="p" href="../read.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../read.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="overload2.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> 138</div> 139</body> 140</html> 141
