How to get UTC time from local time (without date) in PHP?

Question

I've an object where elements are like

i) "StartTime":"0001-01-01T09:30:00+00:00" and "Timezone":"NEW YORK"

The time string is a 24hour format and where "+00:00" is meaningless ie hard coded for all timezone.

I've to convert it to UTC time.

My code-

$startTime = new \DateTime(substr($obj->Session->StartTime, 0, -6));
$startTime->setTimezone(new \DateTimeZone('UTC'));
print_r($startTime);
DateTime Object
(
[date] => 0001-01-01 03:36:40
[timezone_type] => 3
[timezone] => UTC
)

But it should be actually 2:30 pm?

ii) "StartTime":"0001-01-01T08:00:00+00:00" and "Timezone":"LONDON"

Results to

DateTime Object
(
[date] => 0001-01-01 02:06:40
[timezone_type] => 3
[timezone] => UTC
)

It's wrong again.

Any help please?

Answer 1

I would suggest looking into a solution like NTP (network time protocol). It will be very accurate, as well as come with many tools for manipulation and time zone conversion.