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<div class="titlepage"><div><div><h3 class="title">
<a name="asio.reference.buffer_copy"></a><a class="link" href="buffer_copy.html" title="buffer_copy">buffer_copy</a>
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<p>
        <a class="indexterm" name="asio.indexterm.buffer_copy"></a> 
The <code class="computeroutput">asio::buffer_copy</code> function
        is used to copy bytes from a source buffer (or buffer sequence) to a target
        buffer (or buffer sequence).
      </p>
<p>
        Copies bytes from a source buffer sequence to a target buffer sequence.
      </p>
<pre class="programlisting">template&lt;
    typename <a class="link" href="MutableBufferSequence.html" title="Mutable buffer sequence requirements">MutableBufferSequence</a>,
    typename <a class="link" href="ConstBufferSequence.html" title="Constant buffer sequence requirements">ConstBufferSequence</a>&gt;
std::size_t <a class="link" href="buffer_copy/overload1.html" title="buffer_copy (1 of 2 overloads)">buffer_copy</a>(
    const MutableBufferSequence &amp; target,
    const ConstBufferSequence &amp; source);
  <span class="emphasis"><em>» <a class="link" href="buffer_copy/overload1.html" title="buffer_copy (1 of 2 overloads)">more...</a></em></span>
</pre>
<p>
        Copies a limited number of bytes from a source buffer sequence to a target
        buffer sequence.
      </p>
<pre class="programlisting">template&lt;
    typename <a class="link" href="MutableBufferSequence.html" title="Mutable buffer sequence requirements">MutableBufferSequence</a>,
    typename <a class="link" href="ConstBufferSequence.html" title="Constant buffer sequence requirements">ConstBufferSequence</a>&gt;
std::size_t <a class="link" href="buffer_copy/overload2.html" title="buffer_copy (2 of 2 overloads)">buffer_copy</a>(
    const MutableBufferSequence &amp; target,
    const ConstBufferSequence &amp; source,
    std::size_t max_bytes_to_copy);
  <span class="emphasis"><em>» <a class="link" href="buffer_copy/overload2.html" title="buffer_copy (2 of 2 overloads)">more...</a></em></span>
</pre>
<p>
        The <code class="computeroutput">buffer_copy</code> function is available in two forms:
      </p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
            A 2-argument form: <code class="computeroutput">buffer_copy(target, source)</code>
          </li>
<li class="listitem">
            A 3-argument form: <code class="computeroutput">buffer_copy(target, source, max_bytes_to_copy)</code>
          </li>
</ul></div>
<p>
        Both forms return the number of bytes actually copied. The number of bytes
        copied is the lesser of:
      </p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
            <code class="computeroutput">buffer_size(target)</code>
          </li>
<li class="listitem">
            <code class="computeroutput">buffer_size(source)</code>
          </li>
<li class="listitem">
            <code class="computeroutput">If</code> specified, <code class="computeroutput">max_bytes_to_copy</code>.
          </li>
</ul></div>
<p>
        This prevents buffer overflow, regardless of the buffer sizes used in the
        copy operation.
      </p>
<p>
        Note that <a class="link" href="buffer_copy.html" title="buffer_copy"><code class="computeroutput">buffer_copy</code></a>
        is implemented in terms of <code class="computeroutput">memcpy</code>, and consequently it cannot
        be used to copy between overlapping memory regions.
      </p>
<h5>
<a name="asio.reference.buffer_copy.h0"></a>
        <span><a name="asio.reference.buffer_copy.requirements"></a></span><a class="link" href="buffer_copy.html#asio.reference.buffer_copy.requirements">Requirements</a>
      </h5>
<p>
        <span class="emphasis"><em>Header: </em></span><code class="literal">asio/buffer.hpp</code>
      </p>
<p>
        <span class="emphasis"><em>Convenience header: </em></span><code class="literal">asio.hpp</code>
      </p>
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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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