sorting in array

Hi all , I have array value as shown below, i have paste my test php code below: I have problem when doing usort() when 'country' = '', i would like to display records where country = '' last. Any ideas how to do that ? Thanks $arraytest= array(

     array
        (
            'country' => '',
        )
     ,
     array
        (
            'country' => 'Thailand',
        )
     ,
     array
        (
            'country' => 'Singapore',
        )
     ,
     array
        (
            'country' => 'Singapore',
        )
     ,
     array
        (
            'country' => '',
        )
      ,

array

        (
            'country' => '',
        )

, array

        (
            'country' => '',
        )

     );

function cmpcountry($a, $b) {

        $country1 = $a['country'];
        $country2 = $b['country'];

         return ($country1 < $country2) ? -1 : 1;

}

    usort($arraytest,"cmpcountry");
    while(list($name,$value)=each($arraytest)){

echo $name."<br><br>"; while(list($n,$v) = each($arraytest[$name])){

	       echo $v."<br><br>";

}

     }