PHP Manual: Get sorting key for a string

Description

Object-oriented style

public stringfalse Collator::getSortKey(string $string)

Procedural style

stringfalse collator_get_sort_key(Collator $object, string $string)

Return collation key for a string. Collation keys can be compared directly instead of strings, though are implementation specific and may change between ICU library versions. Sort keys are generally only useful in databases or other circumstances where function calls are extremely expensive.

Parameters

object: Collator object.
string: The string to produce the key from.

Return Values

Returns the collation key for the string, or false on failure.

Warning

This function may return Boolean false, but may also return a non-Boolean value which evaluates to false. Please read the section on Booleans for more information. Use the === operator for testing the return value of this function.

Examples

Example #1 collator_get_sort_key example

<?php
$s1 = 'Hello';

$coll = collator_create('en_US');
$res  = collator_get_sort_key($coll, $s1);

echo bin2hex($res);
?>

The above example will output something similar to:

3832404046010901dc08

Example #2 Collator::getSortKey example with usort

<?php
$data = [
    [ 'name' => '🇳🇱 Derick Rethans', 'linked_account' => 'https://phpc.social/users/derickr' ],
    [ 'name' => 'Elephpant', 'linked_account' => 'https://phpc.social/phpc' ],
    [ 'name' => '🇫🇷 Marcus Bointon', 'linked_account' => 'https://phpc.social/users/Synchro' ],
];

/* Create the collator */
$col = new Collator('en');

/* Sort upper-case letters before lower-case letters */
$col->setAttribute(Collator::CASE_FIRST, Collator::UPPER_FIRST);

/* Use a user-defined function with sort, that strips out the emojis */
 */
usort(
    $data,
    function($a, $b) use ($col) {
        /* Remove the character class 'S' (the Symbols), and remove whitespace
         * (with trim) */
        $aName = trim(preg_replace('/\p{S}+/u', '', $a['name']));
        $bName = trim(preg_replace('/\p{S}+/u', '', $b['name']));

                                /* Create the sort key */
        $aKey = $col->getSortKey($aName);
        $bKey = $col->getSortKey($bName);

                                /* Use the sort key to signal which element sorts first */
        return $aKey <=> $bKey;
    }
);

var_dump($data);
?>

The above example will output something similar to:

array(3) {
[0] =>
array(2) {
'name' =>
string(25) "🇳🇱 Derick Rethans"
'linked_account' =>
string(33) "https://phpc.social/users/derickr"
}
[1] =>
array(2) {
'name' =>
string(9) "Elephpant"
'linked_account' =>
string(24) "https://phpc.social/phpc"
}
[2] =>
array(2) {
'name' =>
string(25) "🇫🇷 Marcus Bointon"
'linked_account' =>
string(33) "https://phpc.social/users/Synchro"
}
}

Collator::getSortKey

collator_get_sort_key

Description

Parameters

Return Values

Examples

See Also