Why don't we have two nulls?

Question

I\'ve often wondered why languages with a null representing \"no value\" don\'t differentiate between the passive \"I don\'t know what the value is\"

Answer 1

Within PHP Strict you need to do an isset() check for set variables (or else it throws a warning)

if(!isset($apple))
{
    askForApple();
}

if(isset($apple) && empty($apple))
{
    sulk();
}
else
{
    eatApple();
}