- chunk_split: documentation ( source)
- array_reverse: documentation ( source)
- implode: documentation ( source)
- strrev: documentation ( source)
<?php
$arr = array('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h');
$str = strrev(chunk_split(implode(array_reverse($arr)), 3, ';'));
echo $str;