title: How can I copy value from ostringstream to string?
body: <p>I tried :</p>
  
  <pre><code>ostringstream oss;
  read a string from file and put to oss;
  string str;
  str &lt;&lt; oss.str();// error here "error: no match for ‘operator&gt;&gt;’ in 'oss &gt;&gt; str' "
  </code></pre>
  
  <p>If I use <code>str = oss.str();</code>
  Instead of printing the value of the string, it prints out <code>"....0xbfad75c40xbfad75c40xbf...."</code> likes memory address.<br/>
  Can anybody tell me why?
  Thank you.</p>