prevent double execution of code in PHP

Question

I have a store which works like this:

1. The user adds stuff to his cart on the 1 ^st page
2. The user submits the cart ( POST ), all post data is stored in the session.
3. The user fills out the form on the 2 ^nd page, clicks submit again (second POST )
4. The user comes at the "thank you" page (3 ^rd ), which takes all the session data, and the form POST s the data and mails it.

The problem is, a simple refresh causes an empty table to be sent per email. How can I prevent this? Can I redirect somehow after the execution of the mail function? So the thank you page doesn't do anything on refresh?

Answer 1

You can do by calling the PHP header() function like this:

header('Location: thankyou.php');
exit;

The user will be redirected to the thankyou page and a reload there will not execute your code again.