title: Last key in a std::map
body: <p>I am looking for the highest key value (a defined by the comparison operator) of a std::map.</p>
  
  <p>Is this guaranteed to be </p>
  
  <pre><code>map.rbegin()-&gt;first
  </code></pre>
  
  <p>? </p>
  
  <p>(I am a bit shaky on reverse iterators, and how much freedom there is in the implementation of std::map) </p>
  
  <p>If not, please advise. I cannot change the data structure.</p>