title: Get millisecond part of time
body: <p>I need to get milliseconds from the timer</p>
  
  <pre><code>    // get timer part
      time_t timer = time(NULL);
      struct tm now = *localtime( &amp;timer );
      char timestamp[256];
  
      // format date time
      strftime(timestamp, sizeof(timestamp), "%Y-%m-%d_%H.%M.%S", &amp;now);
  </code></pre>
  
  <p>I want to get like this in C#: </p>
  
  <pre><code>DateTime.Now.ToString("yyyy-MM-dd_HH.mm.ss.ff")
  </code></pre>
  
  <p>I tried using %f or %F but it does work with C++. how can I get %f for milliseconds from tm?</p>