- str_pad: documentation ( source)
<?php
//$start_date =strtotime('2013-02-13 12:02:00');
//$end_date =strtotime('2013-02-20 12:02:00');
//$total = ($end_date- $start_date);
//echo date("Y-m-d H:i:s",$total);
$i = 5;
while($i > 0){
echo str_pad('', $i, 'X') . '<br>';
$i--;
}