Visual C++ build error due to circular includes -

i have 2 classes use each other members.. class one:

#ifndef property_h  #define property_h #include "individualproperty.h" #include "structurizer.h" #include "p_owner.h" #include <windows.h> class p_owner; class p_property {  private:     p_owner _owner;     string ownername;     string propertyaddress;     string taxid;     string postalcode;     bool owes_taxes;     double propertytaxval;     double solidwastetaxval; public:     p_owner getowner() {          return _owner;     }     void setowner(p_owner a) { _owner = a; }      string getpropertyaddress() { return propertyaddress; }     void setpropertyaddress(string a) { propertyaddress = a; }      void settaxid(string a) { taxid = a; }     string gettaxid() { return taxid; }      void setpostalcode(string a) { postalcode = a; }     string getpostalcode() { return postalcode; }      void settaxes(bool a) { owes_taxes = a; }     bool gettaxes() { return owes_taxes; }      void setpropertytaxval(double a) { propertytaxval = a; }     double getpropertytaxval() { return propertytaxval; }      void setsolidwastetaxval(double a) { solidwastetaxval = a; }     double getsolidwastetaxval() { return solidwastetaxval; }      p_property(string _taxid)     {         taxid = _taxid;     }      };  #endif 

and class two:

#ifndef owner_h #define owner_h #include "individualproperty.h" //#include <vector> #include "property.h" class p_property; class p_owner {  private:     string ownername;     string mailingaddress;     string mailingstate;     vector<p_property> ownedproperties;     int numproperties;   public:      string getownername() { return ownername; }     void setownername(string a) { ownername = a; }     string getmailingaddress() { return mailingaddress; }     void setmailingaddress(string a) { mailingaddress = a; }     string getmailingstate() { return mailingstate; }     void setmailingstate(string a) { mailingstate = a; }      p_property getpropertyatindex(int a) {          return ownedproperties.at(a);     }     void addproperty(p_property a) {         ownedproperties.push_back(a);         numproperties++;     }     int getnumproperties() { return numproperties; }       p_owner(string _name, string _addy, string _state)     {         setownername(_name);         setmailingaddress(_addy);         setmailingstate(_state);         numproperties = 0;     }      p_owner()     {         setownername("null");         numproperties = 0;     }     };  #endif 

upon building error: error image

which odd because solution built fine yesterday! have insight on source of issue?

don't include property.h in owner.h. forward declare p_property (as do). move method bodies refer p_property or members owner's header owner's cpp file. that'll break dependencies.

i think have add constructor/destructor decls decl of p_owner , provide bodies (even if empty) in owner.cpp well.

the goal not force field of vector<p_property> instantiate std::vector<p_property> methods until you're compiling body of p_owner. compiler generated constructor/destructor cause vector instantiated header.

it's not clear really want! having p_property directly contain p_owner, , p_owner contain vector of directly contained p_propertys - you're not getting graph structure want! want p_property have pointer p_owner. possibly want p_owner have vector of pointers to p_propertys. previous paragraphs answer question asked, can determine if right question.