Order users by last word of last name

Question

This is probably a typical Dutch issue where you have a last name which can contain multiple words. For example Robin van Persie or Mark de Jong.

Currently I have a list of users ordered by last name, which is the default for get_users. This works fine most of the time but fails when a user has a last name containing more than one word.

For example Mark de Jong is listed between the 'C' and 'E' because of 'de' Jong. However is should be listed between the 'I' and 'K' as Jong should be seen as the word to sort.

Same with Robin van Persie which get listed between the 'U' and 'W' becasue of 'van' Persie. However it should be listed between the 'O' and 'Q' as Persie should be seen as the word to sort.

Is there a way to create a function for this to solve this issue?

Edit: updated with current code:

$allUsers = get_users('orderby=display_name&order=ASC&exclude=1,4');

$users = array();

// Remove subscribers from the list as they won't write any articles

foreach($allUsers as $currentUser)
{
if(!in_array( 'subscriber', $currentUser->roles ))
 {
    $users[] = $currentUser;
 }
}

usort($users, create_function('$a, $b', 'return strnatcasecmp($a->last_name,     
$b->last_name);'));

foreach($users as $user)
{

 // Output 

Thanks in advance!

Answer 1

This should do it:

usort($users, 'wpse_235438_sort_users' );

function wpse_235438_sort_users( $a, $b ) {
    $a_last_name = array_pop( explode( ' ', $a->last_name ) );
    $b_last_name = array_pop( explode( ' ', $b->last_name ) );
    return strnatcasecmp( $a_last_name, $b_last_name );
}

explode() will convert your names into arrays; array_pop() will give you the last item in those arrays, which is what you're looking for. Then you just do the comparison you were already doing to sort them.

Using an anonymous function

Per the PHP page on create_function(), if you're using PHP 5.3 or newer, you should use an anonymous function (or "closure") instead of create_function().

usort($users, function( $a, $b ) {
    $a_last_name = array_pop( explode( ' ', $a->last_name ) );
    $b_last_name = array_pop( explode( ' ', $b->last_name ) );
    return strnatcasecmp( $a_last_name, $b_last_name );
} );

Answer 2

I am guessing that your real question is "How can I achieve this result?".

I would get all users, stick the values into an array and then sort that array.

$names = array();

foreach($users as $user)
{
$names[] = $user->first_name.' '.$user->last_name;
}

usort($names, function($a, $b) {
    $a = substr(strrchr($a, ' '), 1);
    $b = substr(strrchr($b, ' '), 1);
    return strcmp($a, $b);
});

var_dump($names);