- substr: documentation ( source)
- var_dump: documentation ( source)
- str_repeat: documentation ( source)
- strtoupper: documentation ( source)
<?php
foreach(array('day', 'month', 'year') as $dobPart) {
$prefix = substr($dobPart,0,1);
$prefix = str_repeat($prefix,2);
var_dump(strtoupper($prefix));
}