title: Stringstream compile error after including header
body: <p>I'm trying to use a stringstream to read in a string and convert it to various other data types. However, I keep getting the error "Incomplete data type not allowed."</p>
  
  <p>My research on this error has turned up precisely two fixes: make sure to include the header, and use std::stringstream instead of stringstream. Neither of those fixes helped me. Any ideas?</p>
  
  <pre><code>#include &lt;sstream&gt;
  
  bool Arena::addFighter(string info){
      std::stringstream ss;
      ss.getline(info);
      ...
  }
  </code></pre>
  
  <p>Edit: The getline() is not the problem. The code is throwing errors when I try to declare the ss object.</p>