Code Snippet
<?php
date_default_timezone_set("UTC");
echo("<div style='font-family: consolas;'>");
$cur_epochtime = time();
$cur_datetime = new DateTime("@$cur_epochtime");
$human_readible_utc = $cur_datetime->format("Y-m-d H:i:s");
echo("[Current Time] " . $cur_datetime->format("U") . " " . $human_readible_utc . " UTC<br />");
$cur_datetime->setTimezone(new DateTimeZone("Asia/Seoul"));
$human_readible_kst = $cur_datetime->format("Y-m-d H:i:s");
echo("[Current Time] " . $cur_datetime->format("U") . " " . $human_readible_kst . " KST<br />");
$new_datetime_utc_utc = new DateTime($human_readible_utc);
echo("[String to Epochtime UTC-UTC] " . $new_datetime_utc_utc->format("U") . "<br />");
$new_datetime_utc_kst = new DateTime($human_readible_utc, new DateTimeZone("Asia/Seoul"));
$interval = $new_datetime_utc_kst->format("U") - $new_datetime_utc_utc->format("U");
echo("[String to Epochtime UTC-KST] " . $new_datetime_utc_kst->format("U") . " (" . $interval . ")<br />");
$new_datetime_kst_kst = new DateTime($human_readible_kst, new DateTimeZone("Asia/Seoul"));
echo("[String to Epochtime KST-KST] " . $new_datetime_kst_kst->format("U") . "<br />");
echo("<br />9 * 60 * 60 = " . (9 * 60 * 60) . "<br />");
echo("</div>");
?>
[Current Time] 1522194136 2018-03-27 23:42:16 UTC
[Current Time] 1522194136 2018-03-28 08:42:16 KST
[String to Epochtime UTC-UTC] 1522194136
[String to Epochtime UTC-KST] 1522161736 (-32400)
[String to Epochtime KST-KST] 1522194136
9 * 60 * 60 = 32400
References
- https://www.epochconverter.com/programming/php