Is NULL defined as nullptr in C++11?

c++ null c++11 nullptr
Martin Ba picture Martin Ba · Aug 26, 2011 · Viewed 11.6k times · Source

Will C++11 implementations define NULLas nullptr?

Would this be prescribed by the new C++ standard?

Answer

Matthieu M. picture Matthieu M. · Aug 26, 2011

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.

Related questions

What are the advantages of using nullptr?

This piece of code conceptually does the same thing for the three pointers (safe pointer initialization): int* p1 = nullptr; int* p2 = NULL; int* p3 = 0; And so, what are the advantages of assigning pointers nullptr over assigning them the values NULL …

Read More
Why does moving a pointer variable not set it to null?

When implementing move constructors and move assignment operators, one often writes code like this: p = other.p; other.p = 0; The implicitly defined move operations would be implemented with code like this: p = std::move(other.p); Which would be wrong, …

Read More
Checking for NULL pointer in C/C++

In a recent code review, a contributor is trying to enforce that all NULL checks on pointers be performed in the following manner: int * some_ptr; // ... if (some_ptr == NULL) { // Handle null-pointer error } else { // Proceed } instead of int * some_ptr; // ... …

Read More