Get week of month php

I have an array of random dates [not coming from MySQL]. I need to group them by the week as Week1, Week2, and so on upto Week5.

What I have is this:

$dates = array['2015-09-01','2015-09-05','2015-09-06','2015-09-15','2015-09-17'];

What I need is a function to get the week number of the month by providing the date.

I know that I can get the weeknumber by doing date['W',strtotime['2015-09-01']]; but this week number is the number between year [1-52] but I need the week number of the month only, e.g. in Sep 2015 there are 5 weeks:

• Week1 = 1st to 5th
• Week2 = 6th to 12th
• Week3 = 13th to 19th
• Week4 = 20th to 26th
• Week5 = 27th to 30th

I should be able to get the week Week1 by just providing the date e.g.

$weekNumber = getWeekNumber['2015-09-01'] //output 1;
$weekNumber = getWeekNumber['2015-09-17'] //output 3;

Anders

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asked Sep 16, 2015 at 18:18

1

I think this relationship should be true and come in handy:

Week of the month = Week of the year - Week of the year of first day of month + 1

We also need to make sure that "overlapping" weeks from the previous year are handeled correctly - if January 1st is in week 52 or 53, it should be counted as week 0. In a similar fashion, if a day in December is in the first week of the next year, it should be counted as 53. [Previous versions of this answer failed to do this properly.]