Get week number (in the year) from a date PHP

Question

I want to take a date and work out its week number.

So far, I have the following. It is returning 24 when it should be 42.

<?php
$ddate = "2012-10-18";
$duedt = explode("-",$ddate);
$date = mktime(0, 0, 0, $duedt[2], $duedt[1],$duedt[0]);
$week = (int)date('W', $date);
echo "Weeknummer: ".$week;
?>

Is it wrong and a coincidence that the digits are reversed? Or am I nearly there?

Solution 1

Today, using PHP's DateTime objects is better:

<?php
$ddate = "2012-10-18";
$date = new DateTime($ddate);
$week = $date->format("W");
echo "Weeknummer: $week";

---

It's because in mktime(), it goes like this:

mktime(hour, minute, second, month, day, year);

Hence, your order is wrong.

<?php
$ddate = "2012-10-18";
$duedt = explode("-", $ddate);
$date  = mktime(0, 0, 0, $duedt[1], $duedt[2], $duedt[0]);
$week  = (int)date('W', $date);
echo "Weeknummer: " . $week;
?>

Solution 2

$date_string = "2012-10-18";
echo "Weeknummer: " . date("W", strtotime($date_string));

Solution 3

Use PHP's date function
http://php.net/manual/en/function.date.php

date("W", $yourdate)

Solution 4

This get today date then tell the week number for the week

<?php
 $date=date("W");
 echo $date." Week Number";
 ?>

Solution 5

Just as a suggestion:

<?php echo date("W", strtotime("2012-10-18")); ?>

Might be a little simpler than all that lot.

Other things you could do:

<?php echo date("Weeknumber: W", strtotime("2012-10-18 01:00:00")); ?>
<?php echo date("Weeknumber: W", strtotime($MY_DATE)); ?>

View more solutions

Comments

[fedmich]

Just to add, don't forget to set the timezone, using PHP.ini or via date_default_timezone_set('Asia/Singapore');

[Grumpy]

php.net/manual/en/function.date.php

[Mike Sherrill 'Cat Recall']

That's one rule (from ISO 8601, in part). That's what php's date('W', $date) is based on. That's not the only rule, though.

[Suneth Kalhara]

i have different year datas, is that possible to use date('W', $date)

[lukaserat]

You can use Carbon, "github.com/briannesbitt/Carbon" to maximize your skills in Date manipulation. For carbon you can do that by: Carbon::createFromFormat('Y-m-d H', '2012-10-18')->format('W');

[Madara's Ghost]

Actually, you're better off just using PHP's native DateTime objects.

[PeeHaa]

@lukaserat How is that any different from what the accepted answer uses (besides the fact OP has to include an external dependency for something that is already native in the language)?

[lukaserat]

@PeeHaa In many times I don't want to DRY my codes, if there is already good one.

[beetstra]

I would say that the order in mktime() is wrong, not the OP's order. Of course, the latter is easier to change.

[Madara's Ghost]

@beetstra I'd say that today, in 2014, if you use mktime() instead of new DateTime, it's most definitely you who are wrong :)

[Refilon]

As fedmich also suggested, use new DateTime($date, new DateTimeZone('Europe/Amsterdam')); for your own timezone :)

[Farid Abbas]

Yesssss, Its working... Perfect calculation. Thanks @Madara Uchiha.

[Shah Abaz Khan]

If the last week of December is also the first week of next year, (like in 2019), then you will get week number as 1, for dates falling in that week (like 30, 31)

[Loek Bergman]

Welcome to stackoverflow.com. Interesting side point that weeknumbers change differently in different calendars. However, please use a DateTime-object for your code. Furthermore you are not declaring variables before using them. It is allowed in PHP, but not considered best practice. Anyhow, thank you for your first contribution.

[Drea58]

2017-01-01 is a Sunday. Adding a day moves you into the next week, with weeks starting from Monday. 2017-01-01 is the 52th Week of 2016.

[Drea58]

@Shah Abaz Khan In such cases where you need the year information, you can use strftime(). I've added it as an answer to this question.

[peterxz]

This doesnt work, you must do date("W", strtotime($yourdate)) instead.

[S.Walsh]

This is a neat solution for year and week, though unfortunately strftime() has been deprecated as of PHP 8.1.0 php.net/manual/en/function.strftime.php