[fpc-pascal] NULL pointer to array of integer

Vinzent Höfler JeLlyFish.software at gmx.net
Wed Sep 13 19:38:51 CEST 2006

Marc Santhoff wrote:
> Am Mittwoch, den 13.09.2006, 14:00 +0200 schrieb Eduardo:
>> At 10:04 13/09/2006, you wrote:
>>> Hi,
>>> while fiddling with some C'isms I've stumbled over a function in a
>>> library expecting an array of integers *or* a NULL pointer.
>>> How can I hand over any NIL or 0 or something equal to NULL in C that is
>>> accepted by fpc?

By using a pointer to the array instead of an array. Was that too obvious?

>>> Using NIL or 0 does not work certainly...
>> I remember that on c a null pointer has value 0, but in ansi pascal 
>> it has value 23. Don't know if it's still true or if fpc uses the c 
>> value, or both.

This is nonsense. At least for the C version and I doubt that any Pascal 
standard ever stated a value of "23" for NIL.

> ?
> Okay, I'll try that,

DON'T! The "right" way to do such nasty thing would be to dereference a 
NIL pointer constant and then cast it to the according array type. Well, 
I don't know if compiler checks already kick in at that point.

So you're better off with providing an overloaded version which accepts 
a pointer instead of the array type.


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