title: Is calling sizeof (*s.begin()) safe?
body: <p>while doing some TMP :) :(
  I ended up needing the size of the element that STL container holds. 
  I know that usually deref an container.begin() iterator is bad without checking if container isnt empty, but from what I know sizeof is compiletime macro so I <em>guess</em> it is safe. 
  Am I right?</p>
  
  <p>code snippet is :</p>
  
  <pre><code>    for(auto it = t.begin(); it!= t.end(); ++it)
      {
          char* cp = (char*)(&amp;(*it));
          for (size_t i =0 ; i &lt; sizeof *t.begin();++i)
          //...
      }
  </code></pre>