Question

To my understanding, in oppose to javascript which offers the convenient if (var) {}, even if var doesn’t exist, in PHP you have to use if (isset(var)) {}, or if (isset(var) && var) {}.

Today I’ve stumbled upon a login tutorial that seems to be from a reliable source, in which isset is not used:

if(!$_SESSION['id']):

[From the linked page, demo.php section, line 15]

On my local sever, this line breaks when $_SESSION['id'] is not set, which is, IMHO, an expected behaviour. $_SESSION['id'] is not defined prior to this line.

Is there a mysterious way to avoid the annoying isset() check?

Answer 1

Your application doesn’t “break”, because it is just a notice and yes: You should always test the existence of array keys, if you are unsure, whether they exists, or not.

$defaults = array('id' => null);
$session = array_merge($defaults, $_SESSION);

Now you can be sure, that $session has a key id.

However, your can suppress warnings and notices with @

if (!@$_SESSION['id']) { /* .. */ }

But usually if you ever touch the @ key:

• You have a really good reason
• You did something wrong 🙂

In a clean application you need @ only in some very rare cases.

A word at the end: Never use values from outside without validation!