How to get id of submit type button, when button is pressed

I want to print out the id of the button I pressed. The id is set dynamically for each button in a table. This is my HTML code:

    echo '<td><center><input type="submit" id="'.$row['I_ID'].'" class="btn"
name="Add" value ="Add to cart"><center></td><tr>';

And I want to print the id of the button here.

if (isset($_POST['Add'])) {
    $ID = $_GET['id'];
    echo $ID;
    echo '<br/>' . "* The item has been added to your cart.";
}

Answer

If you do not wish to use a hidden field, you could set your submit button like this:

<button type="submit" name="id" value="value">Submit</button>

Then you can catch it with $_GET['id'].

You can have many buttons of type="submit" with the same name (id), and the value will be the one which was clicked, or the first one, if the form was submitted by pressing enter.