Nathan Wiger wrote:
> 
>    undef                     null
>    ------------------------  ------------------------
>    $a = undef;               $a = null;
>    $b = 1;                   $b = 1;
>    $c = $a + b;              $c = $a + $b;
>    $c is 1                   $c is null

Uh, this is a difference in the implementations of the '+'
operator, not the data value undef/null.
Operators that treat undef the way SQL treats null are
trivial to implement.


> The keyword C<null> means that a value is B<known to be unknown>. 

Maybe in your head; not in perl (the implementation).


-- 
John Porter

        We're building the house of the future together.

Reply via email to