Re: Proposal: 6NF

J M Davitt <jdavitt_at_aeneas.net> wrote:

[snip]

>Actually, I wish that C had called the magic value NIL.
>I suspect that it was familiarity with the ASCII NUL -
>which happens to represent the same value as C's NULL -

     It might, but I believe it need not. 0 can be used for NULL, but the actual value might be something else. So much of C is implementation-defined.

>that lead to the on-going confusion. But point that
>there is no point bringing C into the discussion is correct.

     Quite.

[snip]

>Actually, no: C's NULL is nothing more than a zero value
>which marks the end of a string of characters or, by convention,
>the end of a list of pointers or an uninitialized pointer or a
>field of reset bits. (There was some use of an empty string
>called NULL, but that was a horrible mistake.)
>
>In fact, other than use as an end-of-string marker, I suspect
>that most uses of NULL are just C-programmer conventions rather
>than a language feature. It certainly isn't anything as
>sophisticated as a systematic way of dealing with missing data.

     Not quite. It is NUL ('\0') that marks the end of a C string.

     Yes, this is a common beginner error to confuse NULL, NUL (a.k.a. '\0'), and "" (a.k.a. "null string" (never "NULL string")).

Sincerely,

Gene Wirchenko

Computerese Irregular Verb Conjugation:

     I have preferences.
     You have biases.
     He/She has prejudices.