PHP: Avoid undefined index?

Question

Every time a POST value is not equal to the list of values set in an array will return: Undefined Index error, I made an if statement but is not working.

Here\'s the

Answer 1

if(isset($products[$_POST['product']) && $products[$_POST['product'] != "")

Note that a vriable can be empty but also "set" so the what comes after the && is necessary.