How to sort PHP date array

There is such an array, which is composed of multiple dates in (Y-m-d) format. How can we write a program using PHP to sort all dates appearing in an array in descending order?

So if we solve this problem in C/c/Java or any other general programming language, we have to compare the date based on year, month and finally based on day, the method is Store the date in any structure or any other data structure you need.

But in PHP, we can use the strtotime() function, and this problem can be easily solved.

strtotime() function is a PHP function that changes a given date in any format into a timestamp which is essentially a big integer and then while sorting the array we can pass Define a comparison function easily using PHP | usort() function.

The comparator function will accept two date parameters, which will be converted to integer timestamps using the strtotime() function, and then compared with a date sort based on the integer timestamp value.

Built-in functions used:

strtotime():This function changes the given date string to a timestamp (large int value).

usort():This function sorts the given array based on a user-defined comparison function.

The following is the PHP code implementation of the above idea:

<?php 
//PHP程序排序数组的日期
//用户自定义的比较函数
//基于时间戳
function compareByTimeStamp($time1, $time2) 
{ 
    if (strtotime($time1) < strtotime($time2)) 
        return 1; 
    else if (strtotime($time1) > strtotime($time2))  
        return -1; 
    else
        return 0; 
} 
  
// 输入数组 
$arr = array("2018-09-12", "2019-09-06", "2019-09-09"); 
  
// 使用给定的用户定义函数对数组排序
usort($arr, "compareByTimeStamp"); 
  
print_r($arr); 
  
?>

Output:

Array 
( 
    [0] => 2019-09-09 
    [1] => 2019-09-06 
    [2] => 2018-09-12
)

This article is about the method of sorting PHP date arrays, which is also very simple and easy I understand, I hope it helps those in need!

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