How to initialize private static members in C++?

Question

What is the best way to initialize a private, static data member in C++? I tried this in my header file, but it gives me weird linker errors:

class foo
{
           


        

Answer 1

Since C++17, static members may be defined in the header with the inline keyword.

http://en.cppreference.com/w/cpp/language/static

"A static data member may be declared inline. An inline static data member can be defined in the class definition and may specify a default member initializer. It does not need an out-of-class definition:"

struct X
{
    inline static int n = 1;
};