title: is there issue will stringstream.str().c_str()?
body: <p>For Code: </p>
  
  <pre><code>stringstream ss("012345678901234567890123456789012345678901234567890123456789");  
  </code></pre>
  
  <p>some articles said it is wrong for followed usage due to ss.str return temp object and will destructered before call .c_str();</p>
  
  <pre><code> const char* cstr2 = ss.str().c_str();  
  </code></pre>
  
  <p>but I run the example, there is no problem? how to understand?</p>