VFRodriguez

I am starting to learn PHP. I used to make some coding with Visual Foxpro and both have some things in common.
When making a form, in order to avoid that a non real person submits data to the form, i created a new field in the form and called it "suma". In this field the user must include the sum of the current year plus the current day. That means that the value will be the same during the whole day and the value will have 4 digits. For instance 2008+29= 2037
At the beginning of the ACTION .PHP file i included the following piece of code:

<?php
$nValor = abs(substr(date("Y/m/d"),0,4))+abs(substr(date("Y/m/d"),8,2));



if ($_POST["Suma"]<>$nValor)

exit("Sum is incorrect");
else

Echo "Sum is correct, you can continue";

A variant of a captcha trick.