PHP将两个二维数组合并为一个二维数组的方法

$a = array(0 => Array(id => 66,class_name => math),1 => Array(id => 67,class_name => linux ));

$b = array(0 => Array(class_count=> 8),1 => Array(class_count => 2));

$arr = array();

foreach($a as $k=>$r){

   $arr[] = array_merge($r,$b[$k]);

     }