选择的答案不是最正确的答案，因为它将在UTC之外失败。 根据时区(列表)，可能会有时间调整创建“没有”24小时的日子，这将使计算(60*60*24)失败。

这里有一个例子:

date_default_timezone_set('europe/lisbon');
$time1 = strtotime('2016-03-27');
$time2 = strtotime('2016-03-29');
echo floor( ($time2-$time1) /(60*60*24));
 ^-- the output will be **1**

因此，正确的解决方案是使用DateTime

date_default_timezone_set('europe/lisbon');
$date1 = new DateTime("2016-03-27");
$date2 = new DateTime("2016-03-29");

echo $date2->diff($date1)->format("%a");
 ^-- the output will be **2**

从PHP 5.3及以上版本开始，添加了新的日期/时间函数来获得不同:

$datetime1 = new DateTime("2010-06-20");

$datetime2 = new DateTime("2011-06-22");

$difference = $datetime1->diff($datetime2);

echo 'Difference: '.$difference->y.' years, ' 
                   .$difference->m.' months, ' 
                   .$difference->d.' days';

print_r($difference);

结果如下:

Difference: 1 years, 0 months, 2 days

DateInterval Object
(
    [y] => 1
    [m] => 0
    [d] => 2
    [h] => 0
    [i] => 0
    [s] => 0
    [invert] => 0
    [days] => 367
)

希望能有所帮助!

$early_start_date = date2sql($_POST['early_leave_date']);


$date = new DateTime($early_start_date);
$date->modify('+1 day');


$date_a = new DateTime($early_start_date . ' ' . $_POST['start_hr'] . ':' . $_POST['start_mm']);
$date_b = new DateTime($date->format('Y-m-d') . ' ' . $_POST['end_hr'] . ':' . $_POST['end_mm']);

$interval = date_diff($date_a, $date_b);


$time = $interval->format('%h:%i');
$parsed = date_parse($time);
$seconds = $parsed['hour'] * 3600 + $parsed['minute'] * 60;
//        display_error($seconds);

$second3 = $employee_information['shift'] * 60 * 60;

if ($second3 < $seconds)
    display_error(_('Leave time can not be greater than shift time.Please try again........'));
    set_focus('start_hr');
    set_focus('end_hr');
    return FALSE;
}

使用这个:)

$days = (strtotime($endDate) - strtotime($startDate)) / (60 * 60 * 24);
print $days;

现在起作用了

如果你有以秒为单位的时间(即unix时间戳)，那么你可以简单地减去时间并除以86400(秒/天)

这是我的改进版本，显示1年2月25天(s)，如果通过第二个参数。

class App_Sandbox_String_Util {
    /**
     * Usage: App_Sandbox_String_Util::getDateDiff();
     * @param int $your_date timestamp
     * @param bool $hr human readable. e.g. 1 year(s) 2 day(s)
     * @see http://stackoverflow.com/questions/2040560/finding-the-number-of-days-between-two-dates
     * @see http://qSandbox.com
     */
    static public function getDateDiff($your_date, $hr = 0) {
        $now = time(); // or your date as well
        $datediff = $now - $your_date;
        $days = floor( $datediff / ( 3600 * 24 ) );

        $label = '';

        if ($hr) {
            if ($days >= 365) { // over a year
                $years = floor($days / 365);
                $label .= $years . ' Year(s)';
                $days -= 365 * $years;
            }

            if ($days) {
                $months = floor( $days / 30 );
                $label .= ' ' . $months . ' Month(s)';
                $days -= 30 * $months;
            }

            if ($days) {
                $label .= ' ' . $days . ' day(s)';
            }
        } else {
            $label = $days;
        }

        return $label;
    }
}