(PHP 5 >= 5.2.0, PHP 7)
ArrayIterator::uksort — Sort by keys using a user-defined comparison function
This method sorts the elements by keys using a user-supplied comparison function.
Note:
If two members compare as equal, their relative order in the sorted array is undefined.
cmp_function
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. Note that before PHP 7.0.0 this integer had to be in the range from -2147483648 to 2147483647.
No value is returned.