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  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"><span class="keyword">template</span><span class="special">&lt;</span>
  34     <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>
  35     <span class="keyword">typename</span> <a class="link" href="../ConstBufferSequence.html" title="Constant buffer sequence requirements">ConstBufferSequence</a><span class="special">&gt;</span>
  36 <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>
  37     <span class="identifier">SyncRandomAccessWriteDevice</span> <span class="special">&amp;</span> <span class="identifier">d</span><span class="special">,</span>
  38     <span class="identifier">uint64_t</span> <span class="identifier">offset</span><span class="special">,</span>
  39     <span class="keyword">const</span> <span class="identifier">ConstBufferSequence</span> <span class="special">&amp;</span> <span class="identifier">buffers</span><span class="special">,</span>
  40     <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span> <span class="special">&amp;</span> <span class="identifier">ec</span><span class="special">);</span>
  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"><span class="identifier">buffer</span></code></a> function as follows:
 101         </p>
 102 <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>
 103     <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> <span class="identifier">ec</span><span class="special">);</span>
 104 </pre>
 105 <p>
 106           See the <a class="link" href="../buffer.html" title="buffer"><code class="computeroutput"><span class="identifier">buffer</span></code></a>
 107           documentation for information on writing multiple buffers in one go, and
 108           how to use it with arrays, boost::array or std::vector.
 109         </p>
 110 <h6>
 111 <a name="boost_asio.reference.write_at.overload2.h3"></a>
 112           <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>
 113         </h6>
 114 <p>
 115           This overload is equivalent to calling:
 116         </p>
 117 <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>
 118     <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>
 119     <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> <span class="identifier">ec</span><span class="special">);</span>
 120 </pre>
 121 </div>
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 124 <td align="right"><div class="copyright-footer">Copyright &#169; 2003-2014 Christopher M. Kohlhoff<p>
 125         Distributed under the Boost Software License, Version 1.0. (See accompanying
 126         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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