PHP port of JavaScript String slice() method

php_string_slice.php

<?php
/** 
 * PHP port of JavaScript String slice() method 
 * 
 * @param string $str
 * @param int    $start
 * @param int    $end (optional)
 */
function str_slice($str, $start, $end = FALSE)
{
$max = strlen($str);
$start = ($start<0)? $max+$start : $start;
$end = ($end<0)? $max+$end : (($end === FALSE)? $max : $end);

$slice = substr($str, $start, ($end>$start)? $end-$start : 0);

return ($slice === FALSE)? '' : $slice;
}