static const integral class member definition in c++ compile with $(CXX) -std=c++11 main.cpp

b.h

namespace b_space {

struct B
{
    static const int j = 42;
};

}

main.cpp

#include <iostream>
#include "b.h"

namespace a_space {
struct A
{
    static const int i = 23;
};
}  // a_space

int main(void)
{
    std::cout << a_space::A::i << "\n";
    std::cout << b_space::B::j << "\n";
}