title: c++ boost write memory mapped file
body: <p>I am searching for fast writing a file using C++ and boost library. And I would like to use memory mapped file. But Almost all example is about reading.<br>
  Working is very simple. There is a string array. The array elements is about 2 millions.</p>
  
  <pre><code>ofstream outFile("text.txt");
  for (int i = 0; i &lt; 2000000; ++i) {
      outFile &lt;&lt; strArray[i] &lt;&lt; "\n";
  }
  outFile.close();
  </code></pre>
  
  <p>How can I do it using memory mapped file? Where can I find writing file using memory mapped file?  </p>
  
  <p>Thank you for your concerning.</p>