How to Sort a Multidimensional Array by Key: A Step-by-Step Solution?

Sorting a Multidimensional Array by Key: A Comprehensive Guide

Arranging the elements of a multidimensional array in a specific order can be a common requirement in programming. Sorting by a particular key provides an efficient way to organize and retrieve data.

Consider the following multidimensional array containing invitations:

Array (
[0] => Array
    (
        [iid] => 1
        [invitee] => 174
        [nid] => 324343
        [showtime] => 2010-05-09 15:15:00
        [location] => 13
        [status] => 1
        [created] => 2010-05-09 15:05:00
        [updated] => 2010-05-09 16:24:00
    )

[1] => Array
    (
        [iid] => 1
        [invitee] => 220
        [nid] => 21232
        [showtime] => 2010-05-09 15:15:00
        [location] => 12
        [status] => 0
        [created] => 2010-05-10 18:11:00
        [updated] => 2010-05-10 18:11:00
    ))

To sort this array by the "status" key, we can employ the usort() function and a custom comparison function.

Custom Comparison Function

The comparison function determines the order of the elements by comparing their keys. Here's a function that compares based on the "status" key:

function cmp($a, $b) {
    if ($a['status'] == $b['status']) {
        return 0;
    }
    return ($a['status'] < $b['status']) ? -1 : 1;
}

This function returns -1 when $a should come before $b, 1 when $a should come after $b, and 0 when they are equal.

Sorting the Array

We can now sort the array using usort():

usort($array, "cmp");

This will sort the array by the "status" key in ascending order. If we want to reverse the order, we can use rsort():

rsort($array, "cmp");

By utilizing the provided comparison function and sorting functions, we can effortlessly sort multidimensional arrays by any desired key.

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