Can you use the sizeof one member when declaring another member?

Question

Is this legal C++?

struct foo
{
  int a[100];
  int b[sizeof(a) / sizeof(a[0])];
};

GCC 4.6 accepts it, but MSVC 2012 doesn\'t. It seems li

Answer 1

This was illegal in C++03 because these members are nonstatic datamembers.

Starting from C++11 this is legal since in an unevaluated operand you can use nonstatic datamembers without having a corresponding object.