title: C storing 2 numbers in one byte
body: <pre><code>u_char  ip_vhl;     /* version &lt;&lt; 4 | header length &gt;&gt; 2 */
  </code></pre>
  
  <p>I can't get it right , how is this done ? 
  can you give me examples on how to use this byte to store these 2 numbers 
  knowing that each one is 4 bit </p>