PHP get the table data row input value using loop - php

Question

I am having a issue in getting the correct value from the table.
The issue I encountered:
When I choose the second checkbox the and input a quantity, it is Undefined offset: 0
But the value of the checkbox is working and correct.
What I am expecting is when I choose the second or other checkbox (exclude first checkbox), I should get the value of that input field.
HTML
<?php foreach($results as $row) { ?>
<tr>
<td><input type="checkbox" name="products[]" value="<?php echo $row->items_id; ?>"></td>
<td><?php echo $row->item_name; ?></td>
<td><input type="number" name="quantity[]" class="form-control"></td>
</tr>
<?php } ?>
<input type="submit" name="process" class="btn btn-primary" value="Process">
PHP
$quantity = $_POST['quantity'];
$products = $_POST['products'];
$count_selected = count($products);
for($i=0; $i< $count_selected; $i++){
var_dump($quantity[$i]); exit;
}

Answer 1

The problem with checkboxes is that an unchecked one submits no value so your $_POST['products'] and $_POST['quantity'] arrays may have different lengths.
I'd combine using a hidden input with specific array indexes.
For example
<?php foreach($results as $row) : ?>
<tr>
<td>
<input type="hidden" name="products[<?= $row->items_id ?>]" value="0">
<input type="checkbox" name="products[<?= $row->items_id ?>]" value="1">
</td>
<td><?= htmlspecialchars($row->item_name) ?></td>
<td><input type="number" name="quantity[<?= $row->items_id ?>]" class="form-control"></td>
</tr>
<?php endforeach ?>
Then the arrays will have the same indexes and you can iterate them with a foreach
foreach ($_POST['products'] as $itemId => $checked) {
// $checked represents the state of the checkbox
// you can access quantity via $_POST['quantity'][$itemId]
}
You could even create a nice filtered array of quantities via
$selections = $_POST['products'];
$quantities = array_filter($_POST['quantity', function($itemId) use ($selections) {
return $selections[$itemId];
}, ARRAY_FILTER_USE_KEY);

Answer 2

first, define array variable.
$products =array( );
$quantity=array( );
other wise every thing seems fine.