Please use NULL instead of 0 whenever you have a pointer!

[Karlos Mauvtaque]

Dennis Ritchie says that 0 is the 'null pointer'.  Read your reference
manual guys.  There is no place in the language where there is null
pointer ambiguity.  'null pointer's as arguments to function calls
must be cast to the correct pointer type whether you use NULL or 0.
You can't assume that (char *) is the same size as all other pointers so

#define	NULL	((char *)0)

won't do you any good.  I use NULL rather than 0 because it's good style.