Pure virtual functions in C++11

Question

In C++98, the null pointer was represented by the literal 0 (or in fact any constant expression whose value was zero). In C++11, we prefer nullptr

Answer 1

Because the syntax says 0, not expression or some other non-terminal matching nullptr.

For all the time only 0 has worked. Even 0L would be ill-formed because it does not match the syntax.

Edit

Clang allows = 0x0, = 0b0 and = 00 (31.12.2013). That is incorrect and should be fixed in the compiler, of course.