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<div class="titlepage"><div><div><h3 class="title">
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<a name="boost_asio.reference.SyncRandomAccessReadDevice"></a><a class="link" href="SyncRandomAccessReadDevice.html" title="Buffer-oriented synchronous random-access read device requirements">Buffer-oriented
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synchronous random-access read device requirements</a>
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</h3></div></div></div>
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<p>
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In the table below, <code class="computeroutput">a</code> denotes a synchronous random-access read
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device object, <code class="computeroutput">o</code> denotes an offset of type <code class="computeroutput">boost::uint64_t</code>,
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<code class="computeroutput">mb</code> denotes an object satisfying <a class="link" href="MutableBufferSequence.html" title="Mutable buffer sequence requirements">mutable
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buffer sequence</a> requirements, and <code class="computeroutput">ec</code> denotes an object
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of type <code class="computeroutput">error_code</code>.
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</p>
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<div class="table">
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<a name="boost_asio.reference.SyncRandomAccessReadDevice.t0"></a><p class="title"><b>Table 28. Buffer-oriented synchronous random-access read device requirements</b></p>
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<div class="table-contents"><table class="table" summary="Buffer-oriented synchronous random-access read device requirements">
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<colgroup>
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<col>
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<col>
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<col>
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</colgroup>
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<thead><tr>
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<th>
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<p>
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operation
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</p>
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</th>
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<th>
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<p>
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type
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</p>
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</th>
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<th>
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<p>
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semantics, pre/post-conditions
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</p>
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</th>
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</tr></thead>
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<tbody>
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<tr>
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<td>
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<p>
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<code class="computeroutput">a.read_some_at(o, mb);</code>
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</p>
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</td>
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<td>
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<p>
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<code class="computeroutput">size_t</code>
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</p>
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</td>
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<td>
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<p>
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Equivalent to:
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</p>
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<pre class="programlisting">error_code ec;
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size_t s = a.read_some_at(o, mb, ec);
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if (ec) throw system_error(ec);
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return s;
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</pre>
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<p>
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<code class="computeroutput">a.read_some_at(o, mb, ec);</code>
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</p>
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</td>
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<td>
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<p>
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<code class="computeroutput">size_t</code>
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</p>
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</td>
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<td>
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<p>
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Reads one or more bytes of data from the device <code class="computeroutput">a</code>
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at offset <code class="computeroutput">o</code>.<br> <br> The mutable buffer sequence
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<code class="computeroutput">mb</code> specifies memory where the data should be placed.
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The <code class="computeroutput">read_some_at</code> operation shall always fill a buffer
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in the sequence completely before proceeding to the next.<br>
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<br> If successful, returns the number of bytes read and sets
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<code class="computeroutput">ec</code> such that <code class="computeroutput">!ec</code> is true. If an error
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occurred, returns <code class="computeroutput">0</code> and sets <code class="computeroutput">ec</code> such
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that <code class="computeroutput">!!ec</code> is true.<br> <br> If the total size
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of all buffers in the sequence <code class="computeroutput">mb</code> is <code class="computeroutput">0</code>,
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the function shall return <code class="computeroutput">0</code> immediately.
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</p>
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</td>
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</tr>
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</tbody>
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</table></div>
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</div>
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<br class="table-break">
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<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
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<td align="left"></td>
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<td align="right"><div class="copyright-footer">Copyright © 2003-2021 Christopher
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M. Kohlhoff<p>
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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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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