Radio button post data of multiple input fields - php

Question

I have a form in my PHP page which is created by a loop through an array.
echo '<form method="POST" name="add_to_cart_form">
<div id="Product_add_sizes">
<table border="0" cellpadding="2" class="product_txt_font" align="center">
<input type="hidden" name="product_id" value="'.$arr_get_products[$c]['id'].'">';
for ($d = 0; $d < count($arr_get_product_details); $d++)
{
echo '<tr>
<td>
<input type="radio" name="size[]" value="'.$arr_get_product_details[$d]['size'].'">
</td>
<td>
<input class="qty" type="text" size="3" name="amount" value="1">
</td>
</tr>';
}
echo '</table>
<input type="submit" name="add_to_chart" value="Add Product" />
</div>
</form>';
Now when I post this form, I'm searching for a way to get the input of qty which belongs to the selected radio button. I only need the data from the selected radio button row. The other data is not needed as I want to add this product to a shopping cart array.
if (isset($_POST['add_to_chart']))
{
$product_id = $_POST['product_id'];
$size = $_POST['size'][0];
$qty = $_POST['amount'];
}
When posting the page, I know what size is wanted cause of the size[]
array but I can't get the related qty value that matches the selected radio button.
I've tried to treat the qty the same way as the radio button by making it an array qty[] but that will return me all values.
I've search SO and googled a bunch but haven't found a decent answer, but It looks to me that this is used a lot. Please let me know what i'm missing here.
Any help is greatly appreciated!

Answer 1

Radio buttons should all use the same name. Only the selected radio button value is submitted:
<input type="radio" name="Radiosize" value="'.$arr_get_product_details[$d]['size'].'">
then:
$size = $_POST['Radiosize'];
There is no need to look at it as an array - it isn't submitted as one. Radio Buttons are not like checkboxes in form processing.

Answer 2

change
<input class="qty" type="text" size="3" name="amount" value="1">
to
<input class="qty" type="text" size="3" name="amount[]" value="1">
and then you will have 2 arrays that will have same size.
<?php
$size = $_POST['size'][0];
$amount = $_POST['amount'][$size];
?>

Answer 3

Form code:
<input type="radio" name="size" value="'.$arr_get_product_details[$d]['size'].'">
<input class="qty" type="text" size="3" name="amount['.$arr_get_product_details[$d]['size'].']" value="1">
And then you will have value of size. And array of amounts with size keys.
$size = $_POST['size'];
$amount = $_POST['amount'][$size];

Answer 4

I solved the issue by doing the following.
The guys above here all got me on the right track and couldn't have done it without them!
Changed
<input type="radio" name="size[]" value="'.$arr_get_product_details[$d]['size'].'">
<input class="qty" type="text" size="3" name="amount" value="1">
To
<input type="radio" name="size['.$d.']" value="'.$arr_get_product_details[$d]['size'].'">
<input class="qty" type="text" size="3" name="amount['.$d.']" value="1">
Also changed
if (isset($_POST['add_to_chart']))
{
$product_id = $_POST['product_id'];
$size = $_POST['size'][0];
$qty = $_POST['amount'];
}
To this
if (isset($_POST['add_to_chart']))
{
// Array ID key
$key = key($_POST['size']);
$product_id = $_POST['product_id'];
$size = $_POST['size'][$key];
$qty = $_POST['amount'][$key];
}
Works like a charm! Thank you all for your very helpful comments!