How to check if C++ 2011 is enabled on Microsoft and Intel compilers?

Question

I was pretty sure that the compiler is supposed to define __cplusplus such that it indicates which version of the C++ standard is being parsed.

But compiling the following code

#include <iostream>
#include <vector>

int main(int argc, char **argv)
{
  const int cxx_version = __cplusplus;
  std::cout << "C++ version: " << cxx_version << std::endl;

  std::vector<int> v(100, 2);
  int s = 0;
  for(auto i : v) {
    s += i;
  }

  std::cout << "Sum: " << s << std::endl;

  return 0;
}

with

cl cxx11.cpp /Qstd=c++11

or

icl cxx11.cpp /Qstd=c++11

with both Visual Studio 2013 and Intel C++ 16.0 on Windows, produces the unexpected result

C++ version: 199711
Sum: 200

As we can see, the range-based for loop works as expected, but __cplusplus should have been 201102, right?

So my question is three-fold:

• Is /Qstd=c++11 the correct way to enable C++ 2011 on Microsoft or Intel compiler on Windows?
• Is __cplusplus the correct think to check the language version based on the C++ standard? Is there a more reliable alternative for standards-compliant compilers?
• Is there a reliable check for either the Microsoft or Intel compilers in Windows?