Month by week of the year?

Question

I'm trying to get the number of the month of the year by the number of a week of the year and the year. So for example week 1 is in january and returns 1, week 6 is in february so I want 2.

I tried to go with date_parse_from_format('W/Y') but had no success (it's giving me errors).

Is there any way to go with date_parse_from_format() or is there another way?

How do you propose to cope with weeks that start in one month and end in another? — Lazarus, May 25 '11 at 12:34
They should belong to the month they start in, if that makes any sense. — Cobra_Fast, May 25 '11 at 12:35
Precisely which [week numbering system](http://en.wikipedia.org/wiki/Week_number#Week_numbering) do you want to use? — Michael Madsen, May 25 '11 at 12:38
The week numbering system `date('W')` gives back. Which is ISO-8601, beginning on Mondays. — Cobra_Fast, May 25 '11 at 12:43

score 6 · Accepted Answer · answered May 25 '11 at 12:42

6

print date("m",strtotime("2011-W6-1"));

(noting that in 2011, January has six weeks so week 6 (by some definitions) is in month 1).

answered May 25 '11 at 12:42

ADW

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Bug, if we test at this time (2017-01-19), this fuction never return correct week of month 2! – NothingCtrl Jan 19 '17 at 08:43

score 2 · Answer 2 · edited May 23 '17 at 12:01

Using PHP DateTime objects (which is the preferred way of dealing with dates see links below for more info) you can accomplish it this way:

$dateTime = new \DateTime();
$dateTime->setISODate($year,$week);
$month = $dateTime->format('n');

Note that the following will not work as week "W" is not a supported format:

$month = \DateTime::createFromFormat("W/Y ", "1/2015")->format('n');

The format used by this method is the same supported by the function you where trying to use date_parse_from_format, hence the errors.

score 2 · Answer 3 · edited Feb 22 '12 at 12:50

2

Just wanted to add a note for the first answer, the week number should be 01-09 for Weeks 1 through 9 (it will always give month 1 if you don't add the leading zero)

date("m",strtotime("2011-W06-1"));

edited Feb 22 '12 at 12:50

Taryn

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answered Feb 22 '12 at 11:36

Sara.G

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score 1 · Answer 4 · answered May 25 '11 at 12:43

1

Something like this will do, this is also tested and works:

function getMonthByNumber($number,$year)
{
    return date("F",strtotime('+ '.$number.' weeks', mktime(0,0,0,1,1,$year,-1)));
}

echo getMonthByNumber(27,2011);

Hope this helps

answered May 25 '11 at 12:43

RobertPitt

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Month by week of the year?

4 Answers4

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