title: Assign a value to a std::reference_wrapper
body: <p>How can we assign a value to an item wrapped by <code>std::reference_wrapper</code>?</p>
  
  <pre><code>int a[] = {0, 1, 2, 3, 4};
  
  std::vector &lt;std::reference_wrapper&lt;int&gt;&gt; v(a, a+5);
  
  v[0] = 1234;  // Error, can not assign value !
  </code></pre>
  
  <p>Accoring to error, direct assignment is deleted:</p>
  
  <blockquote>
    <p>error: use of deleted function
    'std::reference_wrapper&lt;_Tp>::reference_wrapper(_Tp&amp;&amp;) [with _Tp =
    int]'</p>
  </blockquote>