//定義一個學生數組$students = array(  256=>array('name'=>'jon','grade'=>98.5),  2=>array('name'=>'vance','grade'=>85.1),  9=>array('name'=>'stephen','grade'=>94.0),  364=>array('name'=>'steve','grade'=>85.1),  68=>array('name'=>'rob','grade'=>74.6),);//按照名稱進行排序function name_sort($x, $y){  return strcasecmp($x['name'],$y['name']);}//按照成績進行排序function grade_sort($x,$y){  return ($x['grade'] > $y['grade']);}//應用uasort($students, name_sort);uasort($students, grade_sort);