C++ definition of NULL

[Gabriel Dos Reis]

>>>>> Chad Gatesman <chadg@redrose.net> wrote:

> Jason Merrill wrote:
>> > I am currently porting a very large library that depends on the passing
>> > of NULL into parameters declared as long int.
>> 
>> > egcs appears to define NULL as __null which is a builtin symbol that
>> > treats NULL as `{unknown type} *'.  Therefore, I cannot pass in NULL to
>> > a long int parameter without casting it.
>> 
>> Why would you want to?  Conceptually, NULL is a pointer value.

> I see what you are saying, but unfortunately, this is not my code.  I am
> mearly porting it.  And, technically, it should work since the standard says
> NULL should be a 0 or 0L
       ^^^^^^^^

No. The C++ Standard does not say anything like that. The exact
wording is:

18.1/4
---
  The macro NULL is an implementation-defined C++ null pointer
  constant in this Internnational Standard (4.10).
---

Footnote says:

---
  Possible definitions include 0 and OL, but not (void*)0.
---

Please notice that integer type is not limited to int or long int. It
includes bool, char, short, ...

But I agree with you that the compiler should have selected
func(long) is NULL is of integer type.

-- Gaby