title: Boost Timer 24 hour format
body: <p>I'm using <code>boost::timer::cpu_timer</code> to calculate the "user process time" of an algorithm like so:</p>
  
  <pre><code>boost::timer::cpu_timer timer;
  
  boost::timer::nanosecond_type userTime = timer.elapsed().user;
  </code></pre>
  
  <p>My question is how do I format <code>userTime</code> in <code>HH::MM::SS.mmm</code> format? I know I can write the code myself, but I was expecting Boost to provide some means of doing this.</p>
  
  <p>I came across <a href="http://www.boost.org/doc/libs/1_47_0/doc/html/chrono/users_guide.html#chrono.users_guide.examples.time_point.24_hours_display" rel="nofollow">this example</a>, but it makes use of <code>boost::chrono::duration&lt;Rep, Period&gt;</code>, which I'm not sure how to obtain from <code>boost::timer::nanosecond_type</code>.</p>