<?php
$coll = collator_create( 'en_US' );
$arr = array( 'at', 'às', 'as' );
var_export( $arr );
collator_sort( $coll, $arr );
var_export( $arr );
?>
The above example will output:
array (
0 => 'at',
1 => 'às',
2 => 'as',
)array (
0 => 'as',
1 => 'às',
2 => 'at',
)