- sprintf: documentation ( source)
<?php
$intervals = array(
'1 second' => 1,
'1 minute' => 60 * 60,
'1 day' => 60 * 60 * 24,
'1 year' => 60 * 60 * 24 * 365
);
foreach ($intervals as $interval => $expected) {
$zeroDate = new \DateTime('@0');
$zeroDate->add(\DateInterval::createFromDateString($interval));
echo (sprintf('found %s expected %s', $zeroDate->getTimestamp(), $expected));
}