title: How can the += operator in C be used to demonstrate that the same array index is used for an array reference?
body: <p>I was looking through Expert C Programming by Peter Van Der Linden recently and came across this use for the += operator: </p>
  
  <p>"If you have a complicated array reference and you want to demonstrate that the same index is used for both references, then:</p>
  
  <pre><code>node[i &gt;&gt; 3] += ~(0x01 &lt;&lt; (i &amp; 0x7)); 
  </code></pre>
  
  <p>is the way to go." </p>
  
  <p>As much as I've tried, I can't figure out this code. I'm hoping someone here can explain what is actually going on and why it can be used to demonstrate that the same index is used?</p>