php按字母顺序排列多维数组

Question

I have a multidimensional array that is created with this:

for($i=0; $i<count($sub_results);$i++)
{
    $presenters = array(
        'first_name' => $sub_results[$i]['data'][1]['user_value'],
        'last_name' => $sub_results[$i]['data'][2]['user_value'],
        'preferred_name' => $sub_results[$i]['data'][8]['user_value'],
        'organisation' => $sub_results[$i]['data'][11]['user_value'],
        'portraitFile' => $portrait_file_path.$portrait,
        'Abstract1title' => $sub_results[$i]['data'][19]['user_value'],
        'Abstract1accepted' => $sub_results[$i]['data'][18]['user_value'],
        'Abstract1synopsis' => $sub_results[$i]['data'][22]['user_value'],
        'Abstract1format' => $sub_results[$i]['data'][26]['user_value'],
        'Abstract1coauthors' => $sub_results[$i]['data'][20]['user_value'],
        'Abstract2title' => $sub_results[$i]['data'][28]['user_value'],
        'Abstract2accepted' => $sub_results[$i]['data'][27]['user_value'],
        'Abstract2synopsis' => $sub_results[$i]['data'][31]['user_value'],
        'Abstract2format' => $sub_results[$i]['data'][30]['user_value'],
        'Abstract2coauthors' => $sub_results[$i]['data'][29]['user_value']
    );
}

I want to sort the resulting array alphabetically by last_name. How is this achieved?

With thanks in advance, emrys

Answer 1

This should do it for you. It's case-insensitive. If you have any questions about how it works let me know. Remember that usort accepts the array by reference, meaning that if you want to preserve the original array you will need to make a copy of it.

<?php
    usort($array,function($a,$b) {
        $comparison = strcasecmp($a['last_name'],$b['last_name']);
        if ($comparison == 0) return 0;
        return ($comparison < 0) ? -1 : 1;
    });
?>