多個聲明錯誤 - 虛函數

我有observer.h，client.h和field.h文件。多個聲明錯誤 - 虛函數

在observer.h存在具有

// observer.h 

class Subject { 
public: 
virtual ~Subject(){}; 
Subject(){}; 
virtual void Attach(Observer*); 
virtual void Detach(Observer*); 
virtual void Notify(bool _value); 
virtual bool getCheckedIn(){}; 
private: 
vector < Observer* > _observers; 
};

#ifndef CLIENT_H 
#define CLIENT_H 

#include "Field.h" 

class Client : public Subject { 
public: 
Client(string _name, Field *_field) : client_name(_name) ,field(_field) , checked_in(false) {} 

void setCheckedIn(bool _value){ 
    checked_in = _value; 
    Notify(_value); 
} 

void enterRow(string _row_name){ 
    field->deneme(); 
    setCheckedIn(true); 
} 

bool getCheckedIn(){ return checked_in;} 
private: 
bool checked_in; 
string client_name; 

Field *field; 

}; 

#endif // CLIENT_H

#ifndef Field_H 
#define Field_H 
#include "CreateRow_absFac.h" 
#include "observer_pattern.h" 
#include <vector> 
#include <string> 
using namespace std; 

// Template Class 
class Field{ 
public: 
Field(); 
// Template method 
void field_creator(); 
virtual void setAbstractRow() = 0; 
protected: 
FarmFactory *abstract_row1; 
FarmFactory *abstract_row2; 
FarmFactory *abstract_row3; 

Rows *row1 ; 
Rows *row2 ; 
Rows *row3 ; 
Sensor sensor1; 
};

在編譯時主題類，得到這個錯誤：

ld：重複符號Subject :: Notify（bool）in /Users/barisatamer/Desktop/se311/PROJECT/build/PROJECT.build/Debug/PROJECT.build/Objects-normal/x86_64/Field.o and/Users/barisatamer/desktop/se311/PROJECT/build/PROJECT.build/Debug/PROJECT.build/Objects-normal/x86_64/main.o

如果我刪除了虛函數，它會自動編譯而不會出錯。虛擬功能有什麼問題？

來源

2011-01-06 baris atamer

你的observer.h文件中是否有include guard？ – vdsf 2011-01-06 19:36:49