title: c++ initializing multiset iterator to NULL
body: <p>the issue is I want to initialize a <strong>multiset iterator</strong> to some value, to be able to check later if there was some successful assignment to my iterator or not. Now without this initialization in some cycle of my program I get there some trash and all crashes.
  In pseudocode I'd think about it like that:</p>
  
  <pre><code>multiset&lt;whateverclassA,whateverclassB&gt;::const_iterator init_me = NULL;
  ...//if succesfull, something is assigned to init_me iterator
  if (init_me != NULL)
  //do something
  </code></pre>
  
  <p>however it is not a usual pointer, so simple NULL doesn't suffice probably. 
  Any help appreciated!</p>