c++ - Errors when compiling with include files (Own classes) -

information:microsoft visual studio 2012 ultimate, windows 8 professional, c++. have problem...

qiclassstringoperations.hpp

#include "q.hpp" class qiclassstringoperations {     public:         virtual void fromstring(const qstring& str) = 0;         virtual qstring tostring() = 0; }; 

q.hpp

#include "qstring.hpp" 

qstring.hpp

template <typename type> class cstring {     //... }; typedef cstring<char> qstring; 

in compiling have error:

c:\...\qiclassstringoperations.hpp(13): error c4430: missing type specifier - int assumed. note: c++ not support default-int 

problem line:

virtual void fromstring(const qstring& str) = 0; 

sorry bad english :). can me?

looks qstring in not reconized type? declare qstring?