[RESOLVED] sort array elements by strlen() descending

[solitario]

Hello all.
Could anyone tell me how to sort the elements of an array according the the length of each element, in descending order?

$search_string='Hello this the content of a querystring.';

$keywords=split(' ',$search_string);

So that the result would go something like:

querystring.
content
hello
this
the
of
a

usort() perhaps?
Much appreciated.