Scott Meyers takes a deeper look into uninitialized memory in his recent blog post.

Breaking all the Eggs in C++

by Scott Meyers

From the article:

If you want to make an omelet, so the saying goes, you have to break a few eggs. Think of the omelet you could make if you broke not just a few eggs, but all of them! Then think of what it'd be like to not just break them, but to replace them with newer, better eggs. That's what this post is about: breaking all the eggs in C++, yet ending up with better eggs than you started with.

NULL, 0, and nullptr

NULL came from C. It interfered with type-safety (it depends on an implicit conversion from void* to typed pointers), so C++ introduced 0 as a better way to express null pointers. That led to problems of its own, because 0 isn't a pointer, it's an int. C++11 introduced nullptr, which embodies the idea of a null pointer better than NULL or 0. Yet NULL and 0-as-a-null-pointer remain valid. Why? If nullptr is better than both of them, why keep the inferior ways around?

Backward-compatibility, that's why. Eliminating NULL and 0-as-a-null-pointer would break exiting programs. In fact, it would probably break every egg in C++'s basket. Nevertheless, I'm suggesting we get rid of NULL and 0-as-a-null-pointer, thus eliminating the confusion and redundancy inherent in having three ways to say the same thing (two of which we discourage people from using).