อยากได้ code ที่ใช้ในกการคำนวณ ยอดรวมจำนวนชิ้นของสินค้า.....

<table width="500" border="1">
<tr>
<th bgcolor="#CCCCCC">รหัสสินค้า</th>
<th bgcolor="#CCCCCC">ชื่อสินค้า</th>
<th bgcolor="#CCCCCC">จำนวนชิ้น</th>
<th bgcolor="#CCCCCC">ราคา</th>
<th bgcolor="#CCCCCC">รวม</th>
</tr>
<?
for ($i = 0; $i<count($sess_id); $i++) {
$total_unit = $sess_num[$i] * $sess_price[$i] ;
$total = $total + $total_unit;
$code = sprintf("%05d", $sess_id[$i]);
$total_num =  $sess_num[$i]+$i;
//$total_discount = $total - 40 ;
//$total2=$total+40;
echo "
<tr>
<td align=center>$code</td>
<td>$sess_name[$i]</td>
<td align=center>$sess_num[$i]</td>
<td align=center>$sess_price[$i]</td>
<td align=center>$total_unit</td>
</tr> ";
}
?>
</table>

<table width="502" border="0">
  <tr>
    
    <td width="407" align="right">จำนวนชิ้นทั้งหมด</td>
    <td width="53" align="center">
	<?php echo "$total_num" ?></td>
    <td width="28" align="left">ชิ้น</td>
  </tr>
</table>

<? echo "จำนวนเงินทั้้งหมด  $total  บาท"; ?>

<form  action="basket_cal.php" method="post" >
<script language="JavaScript">
	function chkNumber(ele)
	{
	var vchar = String.fromCharCode(event.keyCode);
	if ((vchar<'0' || vchar>'9') && (vchar = '.')) return false;
	ele.onKeyPress=vchar;
	}
</script>


<table width="545" border="1">
<tr>
<th bgcolor="#CCCCCC">ลบ</th>
<th bgcolor="#CCCCCC">ชื้อสินค้า</th>
<th bgcolor="#CCCCCC">จำนวนชิ้น</th>
<th bgcolor="#CCCCCC">ราคา</th>
<th bgcolor="#CCCCCC">รวม</th>
</tr>
<?
for ($i = 0; $i<count($sess_id); $i++) {
$total_unit = $sess_num[$i] * $sess_price[$i] ;
$total = $total + $total_unit;

echo "
<tr>
<td align=center><input type=checkbox name=id_del[] value=$sess_id[$i]></td>
<td>$sess_name[$i]</td>
<td align=center><input type=text name=id_add[] value=$sess_num[$i] size=4 OnKeyPress='return chkNumber(this)'></td>
<td align=center>$sess_price[$i]</td>
<td align=center>$total_unit</td>
</tr> ";
}
?>
</table>
<p></p>
<p>&nbsp;<a href="product_all.php">+ สั่งสินค้าเพิ่มเติม</a></p>
<p align="right">
<?
echo " <span style=\"color: #FF0000;\">จำนวนเงินทั้งหมด :  $total  บาท</span>" ;
?>
<br><br>
<input type="submit" name="calculate" value="คำนวณใหม่">
<input type="submit" name="complete" value="สั่งซื้อสินค้า">
</p>
</form>

<?
session_start(); ?>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<? if (!$_SESSION['username']){ ?>
	<script language="javascript">
		alert('กรุณาสมัครสมาชิกก่อนซื้อสินค้า');
		window.location="register.php";
	</script>
<?php }
if (count($id_del) == 0){
$id_del = array();
}
for ($i=0; $i<count($sess_id); $i++){
if(!in_array($sess_id[$i],$id_del)){
$temp_id[] = $sess_id[$i];
$temp_name[] = $sess_name[$i];
$temp_price[] = $sess_price[$i];
$temp_num[] = $id_add[$i];
}
}
$sess_id = $temp_id;
$sess_name = $temp_name;
$sess_price = $temp_price;
$sess_num = $temp_num;



if($calculate) { ?>
<script language="javascript">
window.location="basket.php";
</script>

<?php 
} else if ($complete){ ?>
<script language="javascript">
window.location="product_order.php";
</script>

<?php }

?>