uksort Sort an array by keys using a user-defined comparison function &reftitle.description; booluksort arrayarray callbackcmp_function 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. &reftitle.parameters; array The input array. cmp_function The callback comparison function. Function cmp_function should accept two parameters which will be filled by pairs of array 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. &reftitle.returnvalues; &return.success; &reftitle.examples; 1, "the Earth" => 2, "an apple" => 3, "a banana" => 4); uksort($a, "cmp"); foreach ($a as $key => $value) { echo "$key: $value\n"; } ?> ]]> &example.outputs; &reftitle.seealso; usort uasort sort asort arsort ksort natsort rsort