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Comment by hawski | Hacker News Reader

One of musl libc guys wrote quite convincing article about NULL: http://ewontfix.com/11/

There was also discussion on musl mailing list (I don't know is this best link to it): http://www.openwall.com/lists/musl/2013/01/09/1

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The topic was modern C and in modern C environment NULL is defined as

    (void *)0

There is no point in writing longer form and it's still clearer and safer than 0 alone.

C++ is another story with its

    void* hate

built-in. In this land you rather write

    (type*)0

    (type*)NULL

(or

    static_cast<type*>(0)

for extra purists), but as you're denoting pointer type already in this notation, there is not much gain in using NULL instead of 0 (well, beside grepability).

In many cases you can be done with 0 alone in C++, that's true, and in such cases NULL at least poses some intention, but if you're not careful enough, you may end up putting NULL alone (without pointer-to-type cast) in some variadic function and things start to blow up all of a sudden (that is if your NULL integer width isn't the same as pointer width). That's why having a habit of writing

    (type*)0

is a good thing in this land.

Regarding musl check also:

http://git.musl-libc.org/cgit/musl/commit/include/stddef.h?i...

In short, musl's stddef.h has following lines:

    #ifdef __cplusplus
    #define NULL 0L
    #else
    #define NULL ((void*)0)
    #endif

NULL defined as 0L for C++ is nice workaround, but it works only for LP64 platforms.

In the same vein for Windows C++ x64 environment you need NULL to be 0LL, as it is LLP64 platform.

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