title: Qt c++ aggregate 'std::stringstream ss' has incomplete type and cannot be defined
body: <p>I have this function in my program that converts integers to strings:</p>
  
  <pre><code>    QString Stats_Manager::convertInt(int num)
      {
          stringstream ss;
          ss &lt;&lt; num;
          return ss.str();
      }
  </code></pre>
  
  <p>But when ever i run this i get the error:</p>
  
  <pre><code>aggregate 'std::stringstream ss' has incomplete type and cannot be defined
  </code></pre>
  
  <p>Im not really sure what that means. But if you know how to fix it or need any more code please just comment. Thanks.</p>