<?php
// Everything you enter here will be executed by our servers. Try it!
$str = "A, B, C, D, E";
$components = explode(", ", $str);
if (count($components) <= 1) { //If there's only one word, and no commas or whatever.
echo $str;
die(); //You don't have to *die* here, just stop the rest of the following from executing.
}
$last = array_pop($components); //This will remove the last element from the array, then put it in the $last variable.
echo implode(", ", $components) . " & " . $last;