静态结构链接器错误

Question

I'm trying to create a static struct in C++:

static struct Brushes
{
  static HBRUSH white ;
  static HBRUSH yellow ;
} ;

But its not working, I'm getting:

Error 4 error LNK2001: unresolved external symbol "public: static struct HBRUSH__ * Brushes::white"

Why?

The idea is to be able to use Brushes::white , Brushes::yellow throughout the program, without having to create an instance of Brushes .

Answer 1

You have to define the static members somewhere, usually in the .cxx file, eg:

HBRUSH Brushes::white;

The reason is that the header file doesn't make the definition, it only declares it.

Answer 2

You should remove the first static from the struct Brushes line. Then you will need to define the initial values (and declare their memory) in a .cpp file as following:

HBRUSH Brushes::white(some_init_value);
HBRUSH Brushes::yellow(some_init_value);

Answer 3

So you need:

HBRUSH Brushes::white = xxxx;

somewhere in one of your source files. And get rid of that initial static.

you do know about the stock objects in Win32 GDI, right?