PHP把2个二维数组合并一个二维数组

 $a = array(0 => Array(id => 66,class_name => www.iiwnet.com),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]);
 }
 //新的二维数组 $arr