多维数组排序的问题

$array= array(
                        '123456'=>array('aa','bb','cc'),
                         '12345645'=>array('aa','cc'),
                         '1234564555'=>array('aa','dd','cc','bb'),
                          '12364555'=>array('aa','dd','cc'),
);

请问怎么按子数组的长度来排，我想要的结果是

$array= array(
                        '12345645'=>array('aa','cc'),
                        '123456'=>array('aa','bb','cc'),
                        '12364555'=>array('aa','dd','cc'),
                        '1234564555'=>array('aa','dd','cc','bb'),
                        
);

回复讨论(解决方案)

$array = array(  '123456'=>array('aa','bb','cc'),  '12345645'=>array('aa','cc'),  '1234564555'=>array('aa','dd','cc','bb'),  '12364555'=>array('aa','dd','cc'),);foreach($array as $i=>$v) {  $r[] = count($v);  $k[] = $i;}array_multisort($r, $k, $array);print_r(array_combine($k, $array));

Array(    [12345645] => Array        (            [0] => aa            [1] => cc        )    [123456] => Array        (            [0] => aa            [1] => bb            [2] => cc        )    [12364555] => Array        (            [0] => aa            [1] => dd            [2] => cc        )    [1234564555] => Array        (            [0] => aa            [1] => dd            [2] => cc            [3] => bb        ))