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

@$_POST['product']

(with an @) will return the same thing as :

$product = (isset($_POST['product'])) ? $_POST['product'] : null;

Shorter is sweeter !! 4 times less code ! Easier to read and understand.

The @ symbol is the error control operator (AKA the "silence" or "shut-up" operator). It makes PHP suppress any error messages (notice, warning, fatal, etc.).

But beware not to use @ for any other thing, as it would make your code so much harder to debug!

(this will answer your question before the edit)

Answer 2

You should first check to see if $_POST['product'] is set with isset(), like:

if( isset($_POST['product']) ){
    // Do something with $_POST['product']
}

That should suppress the warning.

Answer 3

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

the isset() function will help you avoid the warning

Answer 4

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.

Answer 5

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";
}

Answer 6

You could also try

$product = (isset($_POST['product'])) ? $_POST['product'] : null;

This will set $product to the $_POST value if it exists, or to null if not. Then you could try

if ($product) {
  do_something();
}

or access your array with

$products[$product];

I feel this way it makes your code that little bit easier on the eyes..