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

you can check whether the index 'product' is defined in the same if statement ..

if (isset($_POST['product']) && $products[$_POST['product']] == $_POST['product']) {
    do everything;
}
else {
    echo "This item is not available";
}