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How can I get the last day of the month in PHP?


$a_date = "2009-11-23"

I want 2009-11-30; and given

$a_date = "2009-12-23"

I want 2009-12-31.



t returns the number of days in the month of a given date (see the docs for date):

$a_date = "2009-11-23";
echo date("Y-m-t", strtotime($a_date));
Thursday, September 15, 2022

You can compare the day of the month before and after you add 1 month. If it's not the same, you exceeded the next month.

function add($date_str, $months)
    $date = new DateTime($date_str);

    // We extract the day of the month as $start_day
    $start_day = $date->format('j');

    // We add 1 month to the given date
    $date->modify("+{$months} month");

    // We extract the day of the month again so we can compare
    $end_day = $date->format('j');

    if ($start_day != $end_day)
        // The day of the month isn't the same anymore, so we correct the date
        $date->modify('last day of last month');

    return $date;

$result = add('2011-01-28', 1);   // 2011-02-28
$result = add('2011-01-31', 3);   // 2011-04-30
$result = add('2011-01-30', 13);  // 2012-02-29
$result = add('2011-10-31', 1);   // 2011-11-30
$result = add('2011-12-30', 1);   // 2011-02-28
Sunday, September 18, 2022

you need to escape the a and t as both have special meaning when used as formatting options in date()

echo date('M j at h:i a');

See it in action

Monday, October 17, 2022

You don't need to change the php.ini file if you use date_default_timezone_set(). Just set it to the timezone you will be working in.

Something like this should go in a config file or on the page where you're working with dates (if it is only one page):

Friday, December 23, 2022

calendar.monthrange provides this information:

calendar.monthrange(year, month)
    Returns weekday of first day of the month and number of days in month, for the specified year and month.

>>> import calendar
>>> calendar.monthrange(2002, 1)
(1, 31)
>>> calendar.monthrange(2008, 2)  # leap years are handled correctly
(4, 29)
>>> calendar.monthrange(2100, 2)  # years divisible by 100 but not 400 aren't leap years
(0, 28)


calendar.monthrange(year, month)[1]

seems like the simplest way to go.

Friday, August 19, 2022
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