title: modify boost::asio::buffer from const char*
body: <p>I have <code>const char*</code> returning from one function. It reads file and returns const pointer. I am creating <code>boost::asio::buffer</code> to send this data using <code>boost::send_to</code>. But before sending this buffer I want to modify data inside that buffer. How do I achieve this?</p>
  
  <pre><code>std::unique_ptr&lt;boost::asio::ip::udp::socket&gt; udp_socket;
  const char* data_ptr = readFile();
  udp_socket-&gt;send_to(boost::asio::mutable_buffer(data_ptr, dataSize), endpoint);
  </code></pre>