overload2.html
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<title>read (2 of 16 overloads)</title>
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<div class="titlepage"><div><div><h4 class="title">
<a name="asio.reference.read.overload2"></a><a class="link" href="overload2.html" title="read (2 of 16 overloads)">read (2 of 16 overloads)</a>
</h4></div></div></div>
<p>
Attempt to read a certain amount of data from a stream before returning.
</p>
<pre class="programlisting">template<
typename <a class="link" href="../SyncReadStream.html" title="Buffer-oriented synchronous read stream requirements">SyncReadStream</a>,
typename <a class="link" href="../MutableBufferSequence.html" title="Mutable buffer sequence requirements">MutableBufferSequence</a>>
std::size_t read(
SyncReadStream & s,
const MutableBufferSequence & buffers,
asio::error_code & ec,
typename enable_if< is_mutable_buffer_sequence< MutableBufferSequence >::value >::type * = 0);
</pre>
<p>
This function is used to read a certain number of bytes of data from a
stream. The call will block until one of the following conditions is true:
</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
The supplied buffers are full. That is, the bytes transferred is equal
to the sum of the buffer sizes.
</li>
<li class="listitem">
An error occurred.
</li>
</ul></div>
<p>
This operation is implemented in terms of zero or more calls to the stream's
read_some function.
</p>
<h6>
<a name="asio.reference.read.overload2.h0"></a>
<span><a name="asio.reference.read.overload2.parameters"></a></span><a class="link" href="overload2.html#asio.reference.read.overload2.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 from which the data is to be read. The type must support
the SyncReadStream concept.
</p></dd>
<dt><span class="term">buffers</span></dt>
<dd><p>
One or more buffers into which the data will be read. The sum of
the buffer sizes indicates the maximum number of bytes to read from
the stream.
</p></dd>
<dt><span class="term">ec</span></dt>
<dd><p>
Set to indicate what error occurred, if any.
</p></dd>
</dl>
</div>
<h6>
<a name="asio.reference.read.overload2.h1"></a>
<span><a name="asio.reference.read.overload2.return_value"></a></span><a class="link" href="overload2.html#asio.reference.read.overload2.return_value">Return
Value</a>
</h6>
<p>
The number of bytes transferred.
</p>
<h6>
<a name="asio.reference.read.overload2.h2"></a>
<span><a name="asio.reference.read.overload2.example"></a></span><a class="link" href="overload2.html#asio.reference.read.overload2.example">Example</a>
</h6>
<p>
To read into a single data buffer use the <a class="link" href="../buffer.html" title="buffer"><code class="computeroutput">buffer</code></a>
function as follows:
</p>
<pre class="programlisting">asio::read(s, asio::buffer(data, size), ec);
</pre>
<p>
See the <a class="link" href="../buffer.html" title="buffer"><code class="computeroutput">buffer</code></a>
documentation for information on reading into multiple buffers in one go,
and how to use it with arrays, boost::array or std::vector.
</p>
<h6>
<a name="asio.reference.read.overload2.h3"></a>
<span><a name="asio.reference.read.overload2.remarks"></a></span><a class="link" href="overload2.html#asio.reference.read.overload2.remarks">Remarks</a>
</h6>
<p>
This overload is equivalent to calling:
</p>
<pre class="programlisting">asio::read(
s, buffers,
asio::transfer_all(), ec);
</pre>
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<td align="right"><div class="copyright-footer">Copyright © 2003-2020 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>)
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