PHP中如何计算两个日期之间的差异？

给定两个日期, start_date和end_date。任务是找到两个日期之间的差异。

例子：

Input: start_date: 2016-06-01 22:45:00 
       end_date: 2018-09-21 10:44:01
Output: 2 years, 3 months, 21 days, 11 hours, 59 minutes, 1 seconds

Input: start_date: 2015-05-12 12:37:30 
       end_date: 2018-04-25 12:45:31
Output: 2 years, 11 months, 19 days, 0 hours, 8 minutes, 1 seconds

方法1：采用date_diff()函数找出两个日期之间的差异。

方法2：使用日期时间数学公式来查找两个日期之间的时差。它返回两个指定日期之间的年, 月, 日, 小时, 分钟, 秒。

程序：

<?php
  
// Declare and define two dates
$date1 = strtotime ( "2016-06-01 22:45:00" ); 
$date2 = strtotime ( "2018-09-21 10:44:01" ); 
  
// Formulate the Difference between two dates
$diff = abs ( $date2 - $date1 ); 
  
  
// To get the year divide the resultant date into
// total seconds in a year (365*60*60*24)
$years = floor ( $diff / (365*60*60*24)); 
  
  
// To get the month, subtract it with years and
// divide the resultant date into
// total seconds in a month (30*60*60*24)
$months = floor (( $diff - $years * 365*60*60*24)
                                / (30*60*60*24)); 
  
  
// To get the day, subtract it with years and 
// months and divide the resultant date into
// total seconds in a days (60*60*24)
$days = floor (( $diff - $years * 365*60*60*24 - 
              $months *30*60*60*24)/ (60*60*24));
  
  
// To get the hour, subtract it with years, // months & seconds and divide the resultant
// date into total seconds in a hours (60*60)
$hours = floor (( $diff - $years * 365*60*60*24 
        - $months *30*60*60*24 - $days *60*60*24)
                                    / (60*60)); 
  
  
// To get the minutes, subtract it with years, // months, seconds and hours and divide the 
// resultant date into total seconds i.e. 60
$minutes = floor (( $diff - $years * 365*60*60*24 
          - $months *30*60*60*24 - $days *60*60*24 
                           - $hours *60*60)/ 60); 
  
  
// To get the minutes, subtract it with years, // months, seconds, hours and minutes 
$seconds = floor (( $diff - $years * 365*60*60*24 
          - $months *30*60*60*24 - $days *60*60*24
                 - $hours *60*60 - $minutes *60)); 
  
// Print the result
printf( "%d years, %d months, %d days, %d hours, "
      . "%d minutes, %d seconds" , $years , $months , $days , $hours , $minutes , $seconds ); 
?>

输出如下：

2 years, 3 months, 21 days, 11 hours, 59 minutes, 1 seconds

方法3：此方法用于获取两个指定日期之间的总天数。

<?php
  
// Declare two dates
$start_date = strtotime ( "2018-06-08" );
$end_date = strtotime ( "2018-09-19" );
  
// Get the difference and divide into 
// total no. seconds 60/60/24 to get 
// number of days
echo "Difference between two dates: "
     . ( $end_date - $start_date )/60/60/24;
?>

输出如下：

Difference between two dates: 103