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

I don't have enough rep here to add this as a comment, but IMO it's good style to write your headers with #include guards anyway, which as noted by Paranaix a few hours ago would prevent a multiple-definition error. Unless you're already using a separate CPP file, it's not necessary to use one just to initialize static non-integral members.

#ifndef FOO_H
#define FOO_H
#include "bar.h"

class foo
{
private:
    static bar i;
};

bar foo::i = VALUE;
#endif

I see no need to use a separate CPP file for this. Sure, you can, but there's no technical reason why you should have to.