PHP addition/subtraction of letters
<p>I have the following test code:</p>

<pre><code>&lt;?php

$letter = 'A';
$letter++;
$letter++;

echo $letter.'&lt;br&gt;';  // C

$letter++;
$letter++;
$letter++;

echo $letter.'&lt;br&gt;';  // F

// how to add plus 3 letters
// so that 
// $letter + 3 =&gt; I
</code></pre>

<p>As shown here by using <code>$letter++</code> or <code>$letter--</code> I can go up or down a character. Is there a way I can do something like  <code>$letter + 3</code> so it adds up 3 letters.</p>

<p>I know I can make a function with a loop which will add a char by char and at the end I will get the result. But is there a better way?</p>
