ขอสอบถามเรื่องการรับค่าแบบ Array ซ้อน Array หน่อยค่ะ

<form name="form1" method="post" action="setsubj.php">
    <table>
    <tr><td>Class group :<input type="text" name="class_group[]" value="" />
    subject ID :<input type="text" name="subject_id[]" value="" />
    teacher name :<input type="text" name="teacher_name[]" value="" />
    labroom Name :<input type="text" name="labroom_name[]" value="" />
    Major Name :<input type="text" name="major_name[]" value="" />
    Major year :<input type="text" name="major_year[]" value="" />
    Duration :<input type="text" name="Duration[]" value="" /></td></tr>
    	<tr><td><input type="submit" name="submit" value="OK" /></td></tr>
    </table>
</form>


ไฟล์ที่ส่งข้อมูลมา


<?php
class subj {
	var $class_group;
	var $timeslot_no;
	var $subject_id;
	var $teacher_name;
	var $major_year;
	var $major_name;
	var $labroom_name;
	var $duration;
		
function subj ($class_group=0,$timeslot_no=0,$subject_id=0,$teacher_name=0,$major_year=0,$major_name=0,$labroom_name=0,$duration=0) {
		$this->class_group = $class_group;
		$this->timeslot_no = $timeslot_no;
		$this->subject_id = $subject_id;
		$this->teacher_name = $teacher_name;
		$this->major_year = $major_year;
		$this->major_name = $major_name;
		$this->labroom_name = $labroom_name;
		$this->duration= $duration;
	}
}
$year		= $_POST['year'];
$semester	= $_POST['semester'];

if($_POST!=$_POST['year']or $_POST!=$_POST['semester']){
for($i=0;$i<count($_POST);$i++){
$class_group		= $_POST['class_group'];
$subject_id 		= $_POST['subject_id'];
$teacher_name 		= $_POST['teacher_name'];
$labroom_name 		= $_POST['labroom_name'];
$major_name			= $_POST['major_name'];
$major_year			= $_POST['major_year'];
$duration			= $_POST['duration'];
}
}
for($j=0;$j<$i;$j++){
$chro['$j'] = new subj($class_group['$j'],$timeslot_no['$j']=1,$subject_id['$j'],$teacher_name['$j'],$labroom_name['$j'],$major_name['$j'],$major_year['$j'],$duration['$j']);
$algo = new algo();
$algo->population = array($chro['$j'],$chro['$j'-'$i']);
}
?>