title: What's the difference between istringstream, ostringstream and stringstream? / Why not use stringstream in every case?
body: <p>When would I use <code>std::istringstream</code>, <code>std::ostringstream</code> and <code>std::stringstream</code> and why shouldn't I just use <code>std::stringstream</code> in every scenario (are there any runtime performance issues?).</p>
  
  <p>Lastly, is there anything bad about this (instead of using a stream at all):</p>
  
  <pre><code>std::string stHehe("Hello ");
  
  stHehe += "stackoverflow.com";
  stHehe += "!";
  </code></pre>