in C NULL is just 0. a nullptr in c++ is just a pointer which points to 0. so it's not an undefined value... it's set to 0 on purpose so you can check it. cons

in C NULL is just 0. a nullptr in c++ is just a pointer which points to 0. so it's not an undefined value... it's set to 0 on purpose so you can check it. consider this: char ptr; ptr = (char )0xb8000; before assigning ptr, ptr can be ANY value from 'random memory'. (compiler trickery aside.. because it might initialise it to 0 anyway...) so you want to have: char ptr = NULL; ptr = (char )0xb8000; So you can then do IF(ptr != NULL) { do_stuff(); } you could not check for validity of the ptr value or it being present otherwise. an if(ptr) or if(!ptr) would only work if it's initialised and reset to NULL each time before assignment, so you can validate the assignment. This is not mistake but a tool. for a hardcoded offset like this it might be fair to say you could do if(ptr == 0xb8000) {do_stuff()} but what if it was a ptr returned by a new allocation or so? Or by taking the address of another variable or object? In that case setting things to null and checking them is absolutely essential to assuring your code works like you intended it to. this whole article seems just a bunch of nonsense. for some languages it might hold true, but i can't beleive it would do for any. perhaps this original algol null... who knows.