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<div class="section" title="write_at (1 of 6 overloads)">
<div class="titlepage"><div><div><h4 class="title">
<a name="boost_asio.reference.write_at.overload1"></a><a class="link" href="overload1.html" title="write_at (1 of 6 overloads)"> write_at
(1 of 6 overloads)</a>
</h4></div></div></div>
<p>
Write all of the supplied data at the specified offset before returning.
</p>
<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span>
<span class="keyword">typename</span> <a class="link" href="../SyncRandomAccessWriteDevice.html" title="Buffer-oriented synchronous random-access write device requirements">SyncRandomAccessWriteDevice</a><span class="special">,</span>
<span class="keyword">typename</span> <a class="link" href="../ConstBufferSequence.html" title="Constant buffer sequence requirements">ConstBufferSequence</a><span class="special">></span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">write_at</span><span class="special">(</span>
<span class="identifier">SyncRandomAccessWriteDevice</span> <span class="special">&</span> <span class="identifier">d</span><span class="special">,</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">uint64_t</span> <span class="identifier">offset</span><span class="special">,</span>
<span class="keyword">const</span> <span class="identifier">ConstBufferSequence</span> <span class="special">&</span> <span class="identifier">buffers</span><span class="special">);</span>
</pre>
<p>
This function is used to write a certain number of bytes of data to a random
access device at a specified offset. The call will block until one of the
following conditions is true:
</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
All of the data in the supplied buffers has been written. 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 device's
write_some_at function.
</p>
<a name="boost_asio.reference.write_at.overload1.parameters"></a><h6>
<a name="id1174341"></a>
<a class="link" href="overload1.html#boost_asio.reference.write_at.overload1.parameters">Parameters</a>
</h6>
<div class="variablelist">
<p class="title"><b></b></p>
<dl>
<dt><span class="term">d</span></dt>
<dd><p>
The device to which the data is to be written. The type must support
the SyncRandomAccessWriteDevice concept.
</p></dd>
<dt><span class="term">offset</span></dt>
<dd><p>
The offset at which the data will be written.
</p></dd>
<dt><span class="term">buffers</span></dt>
<dd><p>
One or more buffers containing the data to be written. The sum of the
buffer sizes indicates the maximum number of bytes to write to the
device.
</p></dd>
</dl>
</div>
<a name="boost_asio.reference.write_at.overload1.return_value"></a><h6>
<a name="id1174410"></a>
<a class="link" href="overload1.html#boost_asio.reference.write_at.overload1.return_value">Return
Value</a>
</h6>
<p>
The number of bytes transferred.
</p>
<a name="boost_asio.reference.write_at.overload1.exceptions"></a><h6>
<a name="id1174437"></a>
<a class="link" href="overload1.html#boost_asio.reference.write_at.overload1.exceptions">Exceptions</a>
</h6>
<div class="variablelist">
<p class="title"><b></b></p>
<dl>
<dt><span class="term">boost::system::system_error</span></dt>
<dd><p>
Thrown on failure.
</p></dd>
</dl>
</div>
<a name="boost_asio.reference.write_at.overload1.example"></a><h6>
<a name="id1174478"></a>
<a class="link" href="overload1.html#boost_asio.reference.write_at.overload1.example">Example</a>
</h6>
<p>
To write a single data buffer use the <a class="link" href="../buffer.html" title="buffer"><code class="computeroutput"><span class="identifier">buffer</span></code></a> function as follows:
</p>
<pre class="programlisting"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">write_at</span><span class="special">(</span><span class="identifier">d</span><span class="special">,</span> <span class="number">42</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">data</span><span class="special">,</span> <span class="identifier">size</span><span class="special">));</span>
</pre>
<p>
See the <a class="link" href="../buffer.html" title="buffer"><code class="computeroutput"><span class="identifier">buffer</span></code></a>
documentation for information on writing multiple buffers in one go, and
how to use it with arrays, boost::array or std::vector.
</p>
<a name="boost_asio.reference.write_at.overload1.remarks"></a><h6>
<a name="id1174638"></a>
<a class="link" href="overload1.html#boost_asio.reference.write_at.overload1.remarks">Remarks</a>
</h6>
<p>
This overload is equivalent to calling:
</p>
<pre class="programlisting"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">write_at</span><span class="special">(</span>
<span class="identifier">d</span><span class="special">,</span> <span class="identifier">offset</span><span class="special">,</span> <span class="identifier">buffers</span><span class="special">,</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">transfer_all</span><span class="special">());</span>
</pre>
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<td align="right"><div class="copyright-footer">Copyright © 2003 - 2010 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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