This function will sort an array by its values 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
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
If two members compare as equal, their order in the sorted array is undefined.
Up to PHP 4.0.6 the user defined functions would keep the original order for
those elements, but with the new sort algorithm introduced with 4.1.0 this
is no longer the case as there is no solution to do so in an efficient way.
Note: This function
assigns new keys for the elements in array.
It will remove any existing keys you may have assigned, rather
than just reordering the keys.