Checking for required fields

[Anon]

Just learning PHP and ran across this issue just wanted to know what was the purpose I'm studibg on Shopping carts systems and they use this technique.

heres the code any help is apprecitaed<?

if ((!($sel_product_name)) || (!($sel_product_id)) || (!($sel_qty)) || (!($sel_price)) || (!($sel_price_total)) || (!($pdate))) {
header("Location: http://www.yourdomain.com/show_menu.php3");
exit:
?>

[jariizumi]

!$varname will return a TRUE if the field is empty (i.e., $varname by itself in a conditional will yield in a false if empty). The || signs are for OR's. You can figure it out:

if (FALSE or FALSE or FALSE or FALSE)
will obviously produce a FALSE, which won't catch the filter. However, a
if (FALSE or FALSE or FALSE or TRUE)
will definitely get a TRUE, because it's an OR operator. Thus, if ANY of the fields are empty, then it'll take the viewer to show_menu.php3. That's basically it. Hope this helps 🙂