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

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 or (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?id=c8a9c221 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.