ArrayObject::uasort
ArrayObject::unserialize
ArrayObject
PHP Manual

# ArrayObject::uksort

(PHP 5 >= 5.2.0)

ArrayObject::uksort — Sort the entries by keys using a user-defined comparison function

### Description

public void ArrayObject::uksort ( callable `$cmp_function` )

This function sorts the keys of the entries using a user-supplied comparison function. The key to entry correlations will be maintained.

### Parameters

`cmp_function`

  The callback comparison function.

  Function `cmp_function` should accept two parameters which will be filled by pairs of entry keys. The comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second.

### Return Values

No value is returned.

### Examples

Example #1 ArrayObject::uksort() example

`<?php
function cmp($a, $b) {
$a = preg_replace('@^(a|an|the) @', '', $a);
$b = preg_replace('@^(a|an|the) @', '', $b);
return strcasecmp($a, $b);
}
$array = array("John" => 1, "the Earth" => 2, "an apple" => 3, "a banana" => 4);
$arrayObject = new ArrayObject($array);
$arrayObject->uksort('cmp');
foreach ($arrayObject as $key => $value) {
echo "$key: $value\n";
}
?>`

The above example will output:

    an apple: 3
    a banana: 4
    the Earth: 2
    John: 1

### See Also

- ArrayObject::asort() - Sort the entries by value
- ArrayObject::ksort() - Sort the entries by key
- ArrayObject::natsort() - Sort entries using a "natural order" algorithm
- ArrayObject::natcasesort() - Sort an array using a case insensitive "natural order" algorithm
- ArrayObject::uasort() - Sort the entries with a user-defined comparison function and maintain key association

ArrayObject::uasort
ArrayObject::unserialize
ArrayObject
PHP Manual