I have a date in this format Fri, 15 Jan 2016 15:14:10 +0800, and I want to display time like this 2016-01-15 15:14:10.
What I tried is:
Use H instead:
$test = 'Fri, 15 Jan 2016 15:14:10 +0800';
$t = date('Y-m-d H:i:s',strtotime($test));
echo $t;
H: 24-hour format of an hour with leading zeros 00 through 23
G should be the same, but without leading zeroes though. I suspect that your PHP is set to a different timezone than +0800. Can you confirm your timezone (date_default_timezone_get())?
OP confirmed that his timezone was set to UTC, in which case it maskes perfect sense that it shows 7 in the morning, as date uses PHPs default timezone.
If you want to "inherit" the Timezone, while getting more flexibility, you should switch to DateTime:
echo (new DateTime($test))->format("Y-m-d H:i:s");