title: aggregate 'std::stringstream out' has incomplete type and cannot be defined [C++]
body: <p>I am new to c++ please help me figure out what is wrong with this</p>
  
  <pre><code>string c;
  stringstream out; //aggregate 'std::stringstream out' has incomplete type and cannot be //defined
  out &lt;&lt; it-&gt;second;
  out &lt;&lt; end1;//'end1' was not declared in this scope
  c = out.str();
  </code></pre>