[ Solved -8 Answers] How to find the last day of the month from date

$a_date = "2017-01-23“

We want 2017-01-30; and given

$a_date = "2017-02-23“

We  want 2017-02-31.

php date

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

$a_date = "2040-11-23";
echo date("Y-m-t", strtotime($a_date));

$d = new DateTime( '2040-11-23' ); 
echo $d->format( 'Y-m-t' );

echo cal_days_in_month(CAL_GREGORIAN, 11, 2009); 
// = 30

$week_start = strtotime('last Sunday', time());
$week_end = strtotime('next Sunday', time());

$month_start = strtotime('first day of this month', time());
$month_end = strtotime('last day of this month', time());

$year_start = strtotime('first day of January', time());
$year_end = strtotime('last day of December', time());

echo date('D, M jS Y', $week_start).'<br/>';
echo date('D, M jS Y', $week_end).'<br/>';

echo date('D, M jS Y', $month_start).'<br/>';
echo date('D, M jS Y', $month_end).'<br/>';

echo date('D, M jS Y', $year_start).'<br/>';
echo date('D, M jS Y', $year_end).'<br/>';

$date = Carbon::now();
$date->addMonth();
$date->day = 0;
echo $date->toDateString(); // use toDateTimeString() to get date and time 

$a_date = "2009-11-23";
$date = new DateTime($a_date);
$date->modify('last day of this month');
echo $date->format('Y-m-d');

$date->modify('last day of 1 month');
 echo $date->format('Y-m-d');

public function get_number_of_days_in_month($month, $year) 
{
    // Using first day of the month, it doesn't really matter
    $date = $year."-".$month."-1";
    return date("t", strtotime($date));
}

echo get_number_of_days_in_month(2,2014);