PHP if SESSION exists but is null [duplicate]

This question was not yet really answered (albeit they found a way to foreach over the array to look-up the 'guest' key in the $_SESSION array).

The problem is to check an array entry that is null. Reason is that a check with isset($_SESSION['guest']) returns false as the member is null. Cf. https://php.net/isset .

A function that works is array_key_exists(), as it takes all members into account, including those which are null. It really tests if the key exists in the array.

Example for the case that the guest member is null:

$_SESSION['guest']; # null, no warning
isset($_SESSION['guest']); # false
array_key_exists('guest', $_SESSION); # true

Naturally, using foreach works as well, but it requires more code and the functionality already exists with the array_key_exists() function.

Reference: https://php.net/array_key_exists – see especially Example #2 array_key_exists() vs isset().

Try this:

if(isset($_SESSION['guest']) && is_null($_SESSION['guest']))
{
    // your code
}

if($_SESSION['guest'] == "")
{
    // code
}

You can try using empty instead, for example:

session_start();
if(isset($_SESSION['guest']) && !empty($_SESSION['guest'])) {
    //Session is not null or empty
}
else
{
    //Session is null or empty
}