检查多个$ _SESSION是否为空

I have multiple $_SESSION variables with different names (e.g $_SESSION['blue'], _SESSION['purple'], _SESSION['cream'] etc... is there any way I can use a loop to check which ones are empty and therefore ignore?

foreach ($_SESSION as $key => $value) { 
    if (empty($value)) {
         // ignore 
    }
}

You could use foreach loop

foreach ($_SESSION as $key => $value)
{
  // This goes through the keys that exist.
}