title: C shift zero or shift by zero
body: <p>I am learning program <code>AVR uCs</code>. </p>
  
  <p>An example code snippet contains this line:</p>
  
  <pre><code>DDRC |= (0 &lt;&lt; 0) | (0 &lt;&lt; 1); // PIN C0, C1 as input for buttons
  </code></pre>
  
  <p>I don't understand what sense </p>
  
  <pre><code>(0 &lt;&lt; 0)
  </code></pre>
  
  <p>makes and in general what this line logically does.</p>
  
  <p>I know what the <code>DDRC</code> is I only want to understand this logical operation.</p>
  
  <p><strong>May be the comment helps.</strong></p>