- var_dump: documentation ( source)
- date: documentation ( source)
<?php
$starttime = ['year' => 2019, 'month' => 5, 'day' => 10, 'hour' => 20, 'minute' => 15];
$date = new \DateTime();
$date->setDate($starttime['year'], $starttime['month'], $starttime['day']);
$date->setTime($starttime['hour'], $starttime['minute']);
var_dump($timestamp = $date->getTimestamp());
var_dump(date('Y-m-d H:i:s', $timestamp));