codeigniter undefined offset error - php

Question

I'm currently learning cart system with CI and got some problems
A PHP Error was encountered
Severity: Notice
Message: Undefined offset: 2
Filename: models/main_model.php
Line Number: 241
here's the code:
Controller:
function update_cart(){
$this->main_model->validate_update_cart();
redirect('cart');
}
Model:
function validate_update_cart(){
// Get the total number of items in cart
$total = $this->cart->total_items();
// Retrieve the posted information
$item = $this->input->post('rowid');
$qty = $this->input->post('qty');
// Cycle true all items and update them
for($i=0;$i < $total;$i++)
{
// Create an array with the products rowid's and quantities.
$data = array(
'rowid' => $item[$i], //this is line 241
'qty' => $qty[$i]
);
// Update the cart with the new information
$this->cart->update($data);
}
}
view:
<div id="main">
<?php if(!$this->cart->contents()):
echo 'You don\'t have any items yet.';
else:
?>
<?php echo form_open('cart/update_cart'); ?>
<table width="100%" border="0" cellpadding="0" cellspacing="0">
<thead>
<tr>
<td style="background-color:yellow;">Qty</td>
<td style="background-color:yellow;">Item No/td>
<td style="background-color:yellow;">Description</td>
<td style="background-color:yellow;">Color</td>
<td style="background-color:yellow;">Price</td>
<td style="background-color:yellow;">Sub-Total</td>
<td style="background-color:yellow;">Delete</td>
</tr>
</thead>
<tbody>
<?php $i = 1; ?>
<?php foreach($this->cart->contents() as $items): ?>
<?php echo form_hidden('rowid[]', $items['rowid']); ?>
<tr <?php if($i&1){ echo 'class="alt"'; }?>>
<td>
<?php echo form_input(array('name' => 'qty[]', 'value' => $items['qty'], 'maxlength' => '3', 'size' => '5')); ?>
</td>
<td><a style="font-size:11px;"><?php echo $items['id']?></a></td>
<td><a style="font-size:11px;"><?php echo $items['name']; ?></a></td>
<td><a style="font-size:11px;"><?php echo $items['warna']?></a></td>
<td><a style="font-size:11px;">Rp. <?php echo number_format($items['price'],0,",",".");?></a></td>
<td><a style="font-size:11px;">Rp. <?php echo number_format($items['subtotal'],0,",",".");?></a></td>
<td><img src="<?= base_url();?>assets/image/hapus.png"></img></td>
</tr>
<?php $i++; ?>
<?php endforeach; ?>
<tr>
<td colspan="5"><strong>Total</strong></td>
<td colspan="2"><a align="right"><?php echo $this->cart->format_number($this->cart->total()); ?></a></td>
</tr>
</tbody>
</table>
<p><?php echo "<input type='submit' class='Button' value='Update'>";?></p>
<?php
echo form_close();
endif;
?>
edited the view, complete code.
when i click the update button it returned error live above.
thanks.

Answer 1

It seems that $this->cart->total_items() returns something different from the total items in the $item and $qty arrays. Later on, you are using this result to iterate these arrays, and the loop variable ($i) exceeds the arrays' boundaries.
Change your loop to:
for($i=0;$i < count($item);$i++)
You can choose count($qty) if you prefer, provided that the two arrays contain the same number of elements (which has to be true anyway, in order for the whole algorithm to work).

Answer 2

when you receive the post you should use
rowid[] instead of rowid