How can I sort an array of UTF-8 strings in PHP?

need help with sorting words by utf-8. For example, we have 5 cities from Belgium.

$array = array('Borgloon','Thuin','Lennik','Éghezée','Aubel');
sort($array); // Expected: Aubel, Borgloon, Éghezée, Lennik, Thuin
              // Actual: Aubel, Borgloon, Lennik, Thuin, Éghezée

City Éghezée should be third. Is it possible to use/set some kind of utf-8 or create my own character order?

Solution 1:

intl comes bundled with PHP from PHP 5.3 and it only supports UTF-8.

You can use a Collator in this case:

$array = array('Borgloon','Thuin','Lennik','Éghezée','Aubel');
$collator = new Collator('en_US');
$collator->sort($array);
print_r($array);

Output:

Array
(
    [0] => Aubel
    [1] => Borgloon
    [2] => Éghezée
    [3] => Lennik
    [4] => Thuin
)

Solution 2:

I think you can use strcoll:

setlocale(LC_COLLATE, 'nl_BE.utf8');
$array = array('Borgloon','Thuin','Lennik','Éghezée','Aubel');
usort($array, 'strcoll'); 
print_r($array);

Result:

Array
(
    [0] => Aubel
    [1] => Borgloon
    [2] => Éghezée
    [3] => Lennik
    [4] => Thuin
)

You need the nl_BE.utf8 locale on your system:

fy@Heisenberg:~$ locale -a | grep nl_BE.utf8
nl_BE.utf8

If you are using debian you can use dpkg --reconfigure locales to add locales.

Solution 3:

This script should resolve in a custom way. I hope it help. Note the mb_strtolower function. You need to use it do make the function case insensitive. The reason why I didn't use the strtolower function is that it does not work well with special chars.

<?php

function customSort($a, $b) {
    static $charOrder = array('a', 'b', 'c', 'd', 'e', 'é',
                              'f', 'g', 'h', 'i', 'j',
                              'k', 'l', 'm', 'n', 'o',
                              'p', 'q', 'r', 's', 't',
                              'u', 'v', 'w', 'x', 'y', 'z');

    $a = mb_strtolower($a);
    $b = mb_strtolower($b);

    for($i=0;$i<mb_strlen($a) && $i<mb_strlen($b);$i++) {
        $chA = mb_substr($a, $i, 1);
        $chB = mb_substr($b, $i, 1);
        $valA = array_search($chA, $charOrder);
        $valB = array_search($chB, $charOrder);
        if($valA == $valB) continue;
        if($valA > $valB) return 1;
        return -1;
    }

    if(mb_strlen($a) == mb_strlen($b)) return 0;
    if(mb_strlen($a) > mb_strlen($b))  return -1;
    return 1;

}
$array = array('Borgloon','Thuin','Lennik','Éghezée','Aubel');
usort($array, 'customSort');

EDIT: Sorry. I made many mistakes in the last code. Now is tested.

EDIT {2}: Everything with multibyte functions.

Solution 4:

If you want to use native solution, so i can propose this one

function compare($a, $b)
{
        $alphabet = 'aąbcćdeęfghijklłmnnoóqprstuvwxyzźż'; // i used polish letters
        $a = mb_strtolower($a);
        $b = mb_strtolower($b);

        for ($i = 0; $i < mb_strlen($a); $i++) {
            if (mb_substr($a, $i, 1) == mb_substr($b, $i, 1)) {
                continue;
            }
            if ($i > mb_strlen($b)) {
                return 1;
            }
            if (mb_strpos($alphabet, mb_substr($a, $i, 1)) > mb_strpos($alphabet, mb_substr($b, $i, 1))) {
                return 1;
            } else {
                return -1;
            }
        }
}

usort($needed_array, 'compare');

Not sure, that is the best solution, but it works for me =)