(PHP 4, PHP 5, PHP 7)

uksortSort an array by keys using a user-defined comparison function


uksort ( array &$array , callable $callback ) : bool

uksort() will sort the keys of an array using a user-supplied comparison function. If the array you wish to sort needs to be sorted by some non-trivial criteria, you should use this function.


If two members compare as equal, their relative order in the sorted array is undefined.



The input array.


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.

callback ( mixed $a, mixed $b ) : int

Return Values

Returns TRUE on success or FALSE on failure.


Example #1 uksort() example

<?phpfunction cmp($a, $b){    $a = preg_replace('@^(a|an|the) @', , $a);    $b = preg_replace('@^(a|an|the) @', , $b);    return strcasecmp($a, $b);}$a = array("John" => 1, "the Earth" => 2, "an apple" => 3, "a banana" => 4);uksort($a, "cmp");foreach ($a 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