How do you Calculate Hours from the Beginning of the Year in PHP

Question

I Was Just Wondering How do you Calculate Hours from the Beginning of the Year in PHP 7.1

It's for a countdown clock that is precise

PHP5.1 Not exactly on the bleeding edge of things are you. That does not sit well with your SO Handle. Maybe `Last Millenia Software` would be more appropriate — RiggsFolly, Jul 03 '17 at 13:03
I would think of date_diff() (datetime->diff) But you ask it for an ancient version of php and date_diff is only around since php 5.3: only 8 year ago — Ivo P, Jul 03 '17 at 13:04

apokryfos · Accepted Answer · 2017-07-03T14:00:30.543

0

You can just do:

$diff = date_create()->diff(new DateTime("first day of January ".date("Y")));
$hours = $diff->format("%a")*24 + $diff->h;

As requested here's a way to handle daylight savings:

$transitions = (new DateTimeZone(date_default_timezone_get()))->getTransitions();

$thisYearsTransitions = array_values(array_filter($transitions, function ($v) {
     return substr($v["time"],0,strlen(date("Y"))) == date("Y");
}));
if (count($thisYearsTransitions) == 2 && date_create($thisYearsTransitions[0]) < date_create() && count($thisYearsTransitions)>0 && date_create($thisYearsTransitions[1]) > date_create()) {
    $hours = $hours + ($thisYearsTransitions[0]["offset"]-$thisYearsTransitions[1]["offset"] > 0?1:-1);
}

What this would do is get the DST transitions for this year and if the current date falls after the first and before the second transition it will add/subtract an hour (depending on timezone). Not sure if this would work, have not tested it, but it should.

edited Jul 03 '17 at 14:00

answered Jul 03 '17 at 13:14

apokryfos

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but that's PHP 5.3+. TS is using 5.1 – Ivo P Jul 03 '17 at 13:15
@IvoP I think you're an update behind – apokryfos Jul 03 '17 at 13:15
1

ah : I see TS upgraded his php from 5.1 to 7.1 a minute ago – Ivo P Jul 03 '17 at 13:16
Might be nice to add how to handle a daylight savings shift in there if using localised timezones as well – Mark Baker Jul 03 '17 at 13:45
@MarkBaker Added something, not very confident about it but it might work. – apokryfos Jul 03 '17 at 14:00
@apokryfos - yeah! It adds a nice challenge, especially if you have to consider northern and southern hemispheres, where the order of transitions (forward/backward) is reversed :) – Mark Baker Jul 03 '17 at 14:05

How do you Calculate Hours from the Beginning of the Year in PHP

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