c++ - Undefined reference when instantiating a class -

this main.cpp. here have problem:

i 2 errors:

undefined reference `bankcontroller::bankcontroller(transactionrepository)* @ line 23

and

undefined reference `transactionfilerepository::transactionfilerepository(std::string) @ line 19

for both of them, type c/c++ problem, resource main.cpp

#include "bankgui.h" #include "controller/bankcontroller.h" #include "repository/transactionfilerepository.h" #include "repository/transactionmemoryrepository.h" #include "repository/transactionrepository.h"  #include <qtgui> #include <qapplication> #include <string> #include <iostream> using namespace std;  int main(int argc, char *argv[]){    string path = "datastorage/database.txt";    //instantiate main data repository   transactionrepository* maindatabase;   maindatabase = new transactionfilerepository(path); // <-- error here    //instantiate main controller   bankcontroller* maincontroller;   maincontroller = new bankcontroller(maindatabase); // <-- same error here    //starts gui   qapplication app(argc, argv);   bankgui* mainwidget;   mainwidget = new bankgui(maincontroller);   mainwidget->show();    return app.exec(); } 

i have 3 classes:

• a virtual transactionrepository

• one class implements above transactionmemoryrepository

• one class inherits above transactionmemoryrepository transactionfilerepository

the 3 classes' header files are:

transactionrepository

#ifndef transactionrepository_h_ #define transactionrepository_h_  //---------------------------------------------------------------------------------------------------------------------  #include "../domain/banktransaction.h" #include "../utils/vector.h" #include "../domain/exceptions.h"  //---------------------------------------------------------------------------------------------------------------------  class transactionrepository { public:    /*    *  search , return address of transaction matching id    */   virtual banktransaction* findbyid(int id) = 0;    /*    *  returns list of transactions    */   virtual vector<banktransaction*>findall() = 0;    /*    *  save bank transaction in list    */   virtual void save(banktransaction) throw (repositoryexception) = 0;    /*    *  update transaction    *    */   virtual void update(int id, int day, string type, float amount, string desc) = 0;    /*    *  removes transaction our list    */   virtual void remove(int id) = 0;    /*    *  return total number of transactions our list    */   virtual void getnr() = 0;    /*    *  copy of list    */   virtual void getcopy(vector<banktransaction> list) = 0;    virtual ~transactionrepository(){}  };  //---------------------------------------------------------------------------------------------------------------------  #endif /* transactionrepository_h_ */  //--------------------------------------------------------------------------------------------------------------------- 

transactionmemoryrepository

#ifndef transactionmemoryrepository_h_ #define transactionmemoryrepository_h_  #include "transactionrepository.h" #include "../utils/vector.h"  class transactionmemoryrepository: public transactionrepository { public:   transactionmemoryrepository();   virtual ~transactionmemoryrepository();    /*    *  search , return address of transaction matching id    */   banktransaction* findbyid(int id);    /*    *  returns list of transactions    */   vector<banktransaction*>findall();    /*    *  save bank transaction in list    */   void save(banktransaction) throw (repositoryexception);    /*    *  update transaction    *    */   void update(int id, int day, string type, float amount, string desc);    /*    *  removes transaction our list    */   void remove(int id);    /*    *  return total number of transactions our list    */   void getnr();    /*    *  copy of list    */   void getcopy(vector<banktransaction> list);  protected:    vector<banktransaction*> transactionlist;  };  #endif /* transactionmemoryrepository_h_ */ 

transactionfilerepository

#ifndef transactionfilerepository_h_ #define transactionfilerepository_h_  #include <string> #include "../repository/transactionmemoryrepository.h" #include "../utils/vector.h" #include "../domain/banktransaction.h"  using namespace std;  class transactionfilerepository: public transactionmemoryrepository {  private:   string filename;   vector<banktransaction*> loadfromfile();   void writetofile();  public:   transactionfilerepository(string filepath);   virtual ~transactionfilerepository();   virtual banktransaction* findbyid(string id);   virtual vector<banktransaction*> findall();   virtual void save(banktransaction) throw  (repositoryexception);   virtual void update(banktransaction) throw (repositoryexception);   virtual void remove(string studentid) throw (repositoryexception); };  #endif /* transactionfilerepository_h_ */ 

the .cpp files last 2 classes (since virtual 1 doesn't require .cpp file) don't have implemented in them. thing added protptypes in (.h)eader files.

i've been searching 2 hours on google solutions try doesn't rid of errors.

i should mention c++ qt project working on. had add project properties include paths things work.

all files included exist.