Re: Prevent wildcards from being accepted in filenames (NT mode)

[David Laight]

>   According to the language definition, a constant 0 in
>   a pointer context is converted into a null pointer at
>   compile time.

Indeed even if the stored bit pattern for the 'NULL' pointer isn't
all zero [1], then the literal 0 denotates a NULL pointer.
So:
    char *p = 0;
    if (*(int *)&p != 0)
    	printf(...);
can call printf.

It is also valid to '#define NULL (void *)0' that value is compatible
with function pointers - even though a function pointer can't be assigned
to a 'void *' variable.

David

[1] I don't know of any such C implementation, but I some mainframe OS
have used the all 1 bit pattern for illegal pointers.