Is NULL defined as nullptr in C++11?

From the horse's mouth

C.3.2.4 Macro NULL [diff.null]

1/ The macro NULL, defined in any of <clocale>, <cstddef>, <cstdio>, <cstdlib>, <cstring>, <ctime>, or <cwchar>, is an implementation-defined C++ null pointer constant in this International Standard (18.2).

It is up to each implementation to provide its own definition, gcc if I recall correctly defines it to __nullptr for which it has special checks (verifies that it is not used in arithmetic contexts for example).

So it is possible to define it as nullptr, you will have to check your compiler/Standard Library documentation to see what has been done.

No, NULL is still the same as before. Too many people used the NULL macro in surprising ways, redefining it to nullptr would have broken a lot of code.

To elaborate: people have used NULL for example for many kinds of handle typedefs. If the real type behind such a typedef is not a pointer, defining NULL as nullptr would be a problem. Also, it seems some people have indeed used NULL to initialize numeric types.

At least that is what Microsoft found when they added the nullptr to MSVC10, and why they decided to keep NULL as it always was. Other compilers might choose a different path, but I don't think they would.