Foreach value from POST from form - php

Question

I post some data over to another page from a form. It's a shopping cart, and the form that's being submitted is being generated on the page before depending on how many items are in the cart. For example, if there's only 1 items then we only have the field name 'item_name_1' which should store a value like "Sticker" and 'item_price_1' which stores the price of that item. But if someone has 5 items, we would need 'item_name_2', 'item_name_3', etc. to get the values for each item up to the fifth one.
What would be the best way to loop through those items to get the values?
Here's what I have, which obviously isn't working.
extract($_POST);
$x = 1; // Assuming there's always one item we're on this page, we set the variable to get into the loop
while(${'item_name_' .$x} != '') {
echo ${'item_name' .$x};
$x++;
}
I'm still relatively new to this kind of usage, so I'm not entirely how the best way to deal with it.
Thanks.

Answer 1

First, please do not use extract(), it can be a security problem because it is easy to manipulate POST parameters
In addition, you don't have to use variable variable names (that sounds odd), instead:
foreach($_POST as $key => $value) {
echo "POST parameter '$key' has '$value'";
}
To ensure that you have only parameters beginning with 'item_name' you can check it like so:
$param_name = 'item_name';
if(substr($key, 0, strlen($param_name)) == $param_name) {
// do something
}

Answer 2

Use array-like fields:
<input name="name_for_the_items[]"/>
You can loop through the fields:
foreach($_POST['name_for_the_items'] as $item)
{
//do something with $item
}

Answer 3

If your post keys have to be parsed and the keys are sequences with data, you can try this:
Post data example: Storeitem|14=data14
foreach($_POST as $key => $value){
$key=Filterdata($key); $value=Filterdata($value);
echo($key."=".$value."<br>");
}
then you can use strpos to isolate the end of the key separating the number from the key.

Answer 4

i wouldn't do it this way
I'd use name arrays in the form elements
so i'd get the layout
$_POST['field'][0]['name'] = 'value';
$_POST['field'][0]['price'] = 'value';
$_POST['field'][1]['name'] = 'value';
$_POST['field'][1]['price'] = 'value';
then you could do an array slice to get the amount you need