How to sort an array of names by surname preserving the keys

Question

I have an array as follows:

Array(
    [27] => \'Sarah Green\',
    [29] => \'Adam Brown\',
    [68] => \'Fred Able\'
);

I\'d like

Answer 1

You will probably want to create an auxiliar array with the surnames, keep the key, order it and then reconstruct the original array:

function order_by_surname($names) {
    foreach ($names as $key => $name) {
        $surnames[$key] = array_pop(explode(' ', $name));
    }
    asort($surnames);
    foreach ($surnames as $key => $surname) {
        $ordered[$key] = $names[$key];
    }
    return $ordered;

}

Also, note that you may have problems with this because the surname is not always the last word of a full name when you have two surnames (e.g. John Clark Moore).