Sorting Date Arrays in PHP

When working with PHP, you may encounter situations where you need to sort date arrays in chronological order. One common challenge is ensuring that dates follow the desired format.

For dates in "Mysql" format (Y-m-d or Y-m-d H:i:s), sorting can be straightforward:

$arr = ["2019-11-11", "2019-10-10","2019-11-11", "2019-09-08","2019-05-11"];
sort($arr);

However, for localized or formatted dates, a custom sorting function is necessary. One approach is to convert the dates into sortable format using strtotime():

$arr = ['11/01/2012', '03/16/2022', '12/26/2021', '01/01/2014', '09/02/2013'];
usort($arr, function ($a, $b) {
    return strtotime($a) - strtotime($b);
});

This method converts the dates into Unix timestamps, which can be easily sorted.

It's important to note that using strtotime() assumes that all dates are in the expected format. If different formats are present in your array, consider explicitly defining the format, as explained in the reference article.