如何检查PHP会话是否为空？

Question

Is this bad practice?

if ($_SESSION['something'] == '')
{
    echo 'the session is empty';
}

Is there a way to check if its empty or it is not set? I'm actualy doing this:

if (($_SESSION['something'] == '') || (!isset($_SESSION['something'])) {
    echo 'the session is either empty or doesn\'t exist';
}

Does !isset just checks if a $_SESSION[''] exist and doesn't check if, is there are values in the array or not

Answer 1

I would use isset and empty:

session_start();
if(isset($_SESSION['blah']) && !empty($_SESSION['blah'])) {
   echo 'Set and not empty, and no undefined index error!';
}

array_key_exists is a nice alternative to using isset to check for keys:

session_start();
if(array_key_exists('blah',$_SESSION) && !empty($_SESSION['blah'])) {
    echo 'Set and not empty, and no undefined index error!';
}

Make sure you're calling session_start before reading from or writing to the session array.