class - Qt 4 C++ Getting an error when using 3 classes that use each other, error: field `m_Employer' has incomplete type -

i'm in desperate need of , direction. been trying compile, battling due fact there 3 classes , not hundreds on how includes/forward declarations should work here.

the error marked in person.h.

in addition error, there warning i've marked in main.cpp.

this console app.

thank in advance.

person.h

#ifndef person_h #define person_h #include <qstring>  class employer;  class person {     public:         person(qstring name);         qstring tostring() const;         void setposition(employer newe, position newp);         position getposition() const;     private:         qstring m_name;         bool m_employed;         position m_position;         employer m_employer; //--> error: field `m_employer' has incomplete type. };  #endif // person_h 

person.cpp

#include "employer.h" #include "position.h" #include "person.h"   person::person(qstring name) : m_name(name), m_employed(false), m_position(""), m_employer("") { }    void person::setposition(employer newe, position newp) {     m_position = newp;     m_employed = true;     m_employer = newe; }  position person::getposition()const {     return (m_employed ? m_position : position("professional nose-picker")); }  qstring person::tostring()const {     return m_name + ", employed: " + (m_employed ? "yes" : "no") + ", position: " + getposition().tostring(); } 

employer.h

#ifndef employer_h #define employer_h #include <qstring>  //class position; //class person;  class employer {     public:         employer(qstring name, qstring market = "");         void hire(person &newhire, position pos);         qstring tostring() const;     private:         qstring m_name;         qstring m_market; };  #endif // employer_h 

employer.cpp

#include "employer.h" #include "person.h" #include "position.h"   employer::employer(qstring name, qstring market) : m_name(name), m_market(market) { }  qstring employer::tostring()const {     return m_name + (m_market != "" ? ", market: " + m_market : ""); }  void employer::hire(person &newhire, position pos) {     newhire.setposition(*this, pos); } 

position.h

#ifndef position_h #define position_h #include <qstring>  class position {     public:         position(qstring name, qstring desc = "");         qstring tostring() const;     private:         qstring m_name;         qstring m_desc; };  #endif // position_h 

position.cpp

#include "position.h"  position::position(qstring name, qstring desc)         :m_name(name), m_desc(desc) {}  qstring position::tostring()const {     return m_name + (m_desc != "" ? ", description: " + m_desc : ""); } 

main.cpp

#include <qtcore/qcoreapplication> #include <qtextstream> #include "position.h" #include "person.h" //--warning -> in file included main.cpp:4: #include "employer.h"    int main(int argc, char *argv[]) {     qcoreapplication a(argc, argv);     qtextstream cout(stdout);      person bob("bob");     employer devco("dev co");      cout << bob.tostring() << endl;     bob.setposition(is, position("developer", "software eng"));     cout << bob.tostring() << endl;     cout << devco.tostring() << endl;      return a.exec(); } 

the person class needs know employer , needs employer.h included in rather class forward declaration.

in case person needs know size of employee class have employee stored inside class.

if wanted decouple classes , use forward declaration person have contain pointer (raw or smart) employer.