$date1 = $year.'-'.$month; 
$d = date_create_from_format('Y-m',$date1); 
$last_day = date_format($d, 't');

您也可以将它与datetime一起使用

$date = new \DateTime();
$nbrDay = $date->format('t');
$lastDay = $date->format('Y-m-t');

这应该可以工作:

$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/>';

2行代码，你就完成了:

$oDate = new DateTime("2019-11-23");

// now your date object has been updated with last day of month    
$oDate->setDate($oDate->format("Y"),$oDate->format("m"),$oDate->format("t"));

// or to just echo you can skip the above line using this
echo $oDate->format("Y-m-t");

你的解决方案在这里。

$lastday = date('t',strtotime('today'));

这是一个完整的函数:

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));
}

这将输出如下:

echo get_number_of_days_in_month(2,2014);

输出:28