Get week number in month from date in PHP?

Question

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:

Answer 1

You can also use this simple formula for finding week of the month

$currentWeek = ceil((date("d",strtotime($today_date)) - date("w",strtotime($today_date)) - 1) / 7) + 1;

ALGORITHM :

Date = '2018-08-08' => Y-m-d

1. Find out day of the month eg. 08
2. Find out Numeric representation of the day of the week minus 1 (number of days in week) eg. (3-1)
3. Take difference and store in result
4. Subtract 1 from result
5. Divide it by 7 to result and ceil the value of result
6. Add 1 to result eg. ceil(( 08 - 3 ) - 1 ) / 7) + 1 = 2

Answer 2

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

Implemented in PHP you get this:

function weekOfMonth($date) {
    //Get the first day of the month.
    $firstOfMonth = strtotime(date("Y-m-01", $date));
    //Apply above formula.
    return intval(date("W", $date)) - intval(date("W", $firstOfMonth)) + 1;
}

To get weeks that starts with sunday, simply replace both date("W", ...) with strftime("%U", ...).