- abs: documentation ( source)
- floor: documentation ( source)
- strtotime: documentation ( source)
<?php
for($i=1;$i<=100;$i++){
$daysAfterTime = floor( abs( strtotime('2014-01-01') - strtotime('2014-01-01 +'.$i.' days') )/(60*60*24));
echo $daysAfterTime.PHP_EOL;
}