- var_dump: documentation ( source)
<?php
$startBookTime = new DateTime();
echo $startBookTime->format('H:m').'<br/>' ;
$overTime = new DateTime();
$overTime->setTime(19, 5);
echo $overTime->format('H:m').'<br/>' ;
var_dump($startBookTime->format('U') < $overTime->format('U') );