Natural English list grammar from an array.

natlist.php

<?php
/**
 * @author Jonathan Lettman
 * @param input Array or String to convert to a natural list.
 * @param alphabetical Option to sort the list input alphabetically before turning it into a string.
 * @return string Product of Natlist in the natural English grammar of a list.
 */
function natlist($input, $alphabetical = false)
{
	if(is_array($input)) $arrayCount = count($input);
	else return $input;

	if($alphabetical) natsort($input);

	switch($arrayCount)
	{
		case 0:	return ''; break;
		case 1:	return $input[0]; break;
		case 2:	return implode(' and ', $input); break;

		default: # Greater than 2.
			$pieces2 = $input[$arrayCount - 1];
			unset($input[$arrayCount - 1]);

			$pieces1 = implode(', ', $input);
			return $pieces1.', and '.$pieces2;
			break;
	}
}