Re: Nulls get converted to 0 problem

On Fri, 6 Jun 2003, Mattias Kregert wrote:

> 1. Imagine a table with dates and weather conditions. How would you
>    differ between "zero degrees" and "no data entered yet"? You would
>    have to add a column (degrees_valid boolean). Having the NULL value
>    makes things much easier.
>
> 2. In OO languages (c++, java, and so on), a null pointer is very
>    different from a pointer to an object - even if that object contains
>    the value 0 (zero) or an empty string (""). The "practices" you refer
>    to does not apply/is not inherent in all languages. NULL means that
>    the variable points to nothing at all. "" means that there is some
>    address/space allocated.
>   Example:
>     String mystring = NULL;  // pointer mystring points to nothing (no
>     allocation)
>     String mystring = new String("");  // pointer mystring points to a
>     memory location, which currently holds the empty data "".

<click!>

Thank you Mattias, the differences (and similarities) are now clear.

Cheers!
Jon

--
Jon Earle

SAVE FARSCAPE http://www.savefarscape.com/