title: Element at index in a std::set?
body: <p>I've stumbled upon this problem: I can't seem to select the item at the index' position in a normal <code>std::set</code>. Is this a bug in STD?</p>
  
  <p>Below a simple example:</p>
  
  <pre><code>#include &lt;iostream&gt;
  #include &lt;set&gt;
  
  int main()
  {
      std::set&lt;int&gt; my_set;
      my_set.insert(0x4A);
      my_set.insert(0x4F);
      my_set.insert(0x4B);
      my_set.insert(0x45);
  
      for (std::set&lt;int&gt;::iterator it=my_set.begin(); it!=my_set.end(); ++it)
          std::cout &lt;&lt; ' ' &lt;&lt; char(*it);  // ups the ordering
  
      //int x = my_set[0]; // this causes a crash!
  }
  </code></pre>
  
  <p>Anything I can do to fix the issue?</p>