Php strtotime

<?php


/*
1 day   = 24 (hr) = 1440 (m) = 86400 (s)
1 hr = 60 (m) = 3600 (s)
1 minute = 60 (s)
*/



$start_ = "2020-3-17 10:00:00";

$now    = time();

$date_ = floor(($now - strtotime($start_)));

echo floor($date_ / 86400).'天<br/>';

echo floor(($date_ % 86400) / 3600).'小時<br/>';

echo floor(($date_ % 86400) /3600 * 60).'總分<br/>';

echo floor((($date_ % 86400) % 3600)/60).'分鐘<br/>';

echo floor((($date_ % 86400) % 3600)%60).'秒<br/>';

?>