c++ - Undefined reference to a static member -

i'm using cross compiler. code is:

class windowstimer{ public:   windowstimer(){     _frequency.quadpart = 0ull;   }  private:   static large_integer _frequency; }; 

i following error:

undefined reference `windowstimer::_frequency'

i tried change to

large_integer _frequency.quadpart = 0ull; 

or

static large_integer _frequency.quadpart = 0ull; 

but i'm still getting errors.

anyone knows why?

you need define _frequency in .cpp file.

i.e.

large_integer windowstimer::_frequency;