function get_daydiff($end_date,$today)
{
    if($today=='')
    {
        $today=date('Y-m-d');
    }
    $str = floor(strtotime($end_date)/(60*60*24)) - floor(strtotime($today)/(60*60*24));
    return $str;
}
$d1 = "2018-12-31";
$d2 = "2018-06-06";
echo get_daydiff($d1, $d2);

你可以通过简单的方法找到约会对象

<?php
$start  = date_create('1988-08-10');
$end    = date_create(); // Current time and date
$diff   = date_diff( $start, $end );

echo 'The difference is ';
echo  $diff->y . ' years, ';
echo  $diff->m . ' months, ';
echo  $diff->d . ' days, ';
echo  $diff->h . ' hours, ';
echo  $diff->i . ' minutes, ';
echo  $diff->s . ' seconds';
// Output: The difference is 28 years, 5 months, 19 days, 20 hours, 34 minutes, 36 seconds

echo 'The difference in days : ' . $diff->days;
// Output: The difference in days : 10398

最简单的方法来找出两个日期之间的天数差

$date1 = strtotime("2019-05-25"); 
$date2 = strtotime("2010-06-23");

$date_difference = $date2 - $date1;

$result =  round( $date_difference / (60 * 60 * 24) );

echo $result;

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!

看看所有的答案，我写了一个通用函数，适用于所有的PHP版本。

if(!function_exists('date_between')) :
    function date_between($date_start, $date_end)
    {
        if(!$date_start || !$date_end) return 0;

        if( class_exists('DateTime') )
        {
            $date_start = new DateTime( $date_start );
            $date_end   = new DateTime( $date_end );
            return $date_end->diff($date_start)->format('%a');
        }
        else
        {           
            return abs( round( ( strtotime($date_start) - strtotime($date_end) ) / 86400 ) );
        }
    }
endif;

一般来说，我使用“DateTime”来查找两个日期之间的天数。但如果出于某种原因，一些服务器设置没有启用'DateTime'，它将使用'strtotime()'简单(但不安全)计算。

使用这个简单的函数。声明函数

<?php
function dateDiff($firstDate,$secondDate){
    $firstDate = strtotime($firstDate);
    $secondDate = strtotime($secondDate);

    $datediff = $firstDate - $secondDate;
    $output = round($datediff / (60 * 60 * 24));
    return $output;
}
?>

像这样调用这个函数

<?php
    echo dateDiff("2018-01-01","2018-12-31");    

// OR

    $firstDate = "2018-01-01";
    $secondDate = "2018-01-01";
    echo dateDiff($firstDate,$secondDate);    
?>