How doest $_GET"id" variable know that "id" is a "product_id"?

$_GET is a PHP super global which is parsing Browser URL and scanning&retrieving given parameter by name.

For example if your URL is like: http://example.com?my_param=somevalue

Using PHP and $_GET, it is possible to fetch that value like this:

<?php
$myParam = $_GET['my_param'];
?>

Here is some more information about $_GET: http://php.net/manual/en/reserved.variables.get.php

Do you mean this?:

<?php
$product_id = $_GET['id'];
?>

Yes. Now with regards to your code snippet - How does GET request know, what value to put between square brackets? I think, it literally scans the browser entry for piece of text like this. blah blah blah - ohh... there it is "id=...". Match-Hurray!! I just would like someone to confirm, my understanding is ok.

Cheers Marcin

Just to explain this to others in the context of the course.

Earlier in this course you programmed your shirts.php file to set a GET variable in the url (around line 17 or so)

echo '<a href="shirt.php?id=' . $product_id . '">';

When you put a question mark(?) after the url, you can set a variable and assign(=) it a value.

That $product_id variable comes from your array in your products.php file.

If you look at your url every time you click on a different shirt, the id(or whatever you want to call the variable) changes to it's corresponding id set in the array. PHP knows the $_GET action is to look for that variable.

So, in a nutshell this is what you did:

set key in the $products array>>>assigned the key as a value to the variable $product_id>>> assigned the $product_id as a value to the GET variable in your url>>>

And that's how you make dynamic pages work! Hope that made sense!

You must know with key is in the url query string. If you want to use another key you have to update your script.

http://example.com/?page=edit&id=5&array[]=a&array[]=b

<?php
$page = $_GET['page']; // edit
$id = $_GET['id']; // 5
$array = $_GET['array'];
echo $array[0]; // a
echo $array[1]; // b
?>