Defining constexpr static data members

Question

So, I\'m aware that in C++ static members can be initialized inside the class if they are a const literal type like the following

class test{
public:
               


        

Answer 1

C++17 inline variables

In C++17 if you also mark the static member as inline, then I believe that you can odr-use it freely or have multiple definitions across compilation units, e.g.:

#include 

class MyClass {
    public:
        inline static constexpr int i = 42;
};


int main() {
    const int &cs = MyClass::i;
    std::cout << cs << std::endl;
    std::cout << &MyClass::i << std::endl;
}

More info at: How do inline variables work?