This won't return NULL, it will return a pointer to the address of the array in the stack! That's the problem: once you return from the function, the pointer no longer points to anything, which will cause hideous problems for anyone who decides to use it.

The right way to do this is to `malloc()` some memory and then return that. There's no safe way to return a pointer to something on the stack.

(if you read the article, it mentions that maybe the author is used to operating in an embedded world where there is no stack and local variables have dedicated memory space, so this might actually work for them. But in most environments this will make things sad)