title: Determine if char is a num or letter
body: <p>How do I determine if a <code>char</code> in C such as <code>a</code> or <code>9</code> is a number or a letter?</p>
  
  <p>Is it better to use:</p>
  
  <pre><code>int a = Asc(theChar);
  </code></pre>
  
  <p>or this?</p>
  
  <pre><code>int a = (int)theChar
  </code></pre>