Re: NULL versus 0

On 9/27/21 1:47 AM, Juha Nieminen wrote:
> Paavo Helde <[email protected]> wrote:
>> In C++ (unlike C), NULL is a macro defined to 0, so there is no 
>> difference.
> 
> Actually, many standard library implementations define NULL to be
> nullptr (if we are in C++11 or newer).
> 
> (I haven't checked the standard, but this tells me that the standard does
> not mandate NULL to be defined as 0.)

The mandate is quite clear:

"The macro NULL is an implementation-defined null pointer constant."
(17.2p3).

Note that "null pointer constant" has a different definition in C++ than
in C, and when compiling using C++, NULL can have a definition that
meets C++ requirements rather than C requirements. In particular, that
means that NULL can expand to "a prvalue of type std::nullptr_t." (7.3.11p1)