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Error: Forward Structure Declaration

I am getting the error:

proprietario.cpp:36: error: invalid use of incomplete type ‘struct Motocicleta’
proprietario.h:12: error: forward declaration of ‘struct Motocicleta’

Motocicleta.h:

#ifndef __MOTOCICLETA__
#define __MOTOCICLETA__
#include <iostream>
#include "veiculo.h"
#include "proprietario.h"
using namespace std;
class Proprietario;
class Motocicleta:public Veiculo{

public:
  Motocicleta(int nPassageiros, string modelo, string placa, int aFabricacao, Proprietario* pai, int nRodas, int aro);
  ~Motocicleta();
  Motocicleta (const Motocicleta& source);
  Motocicleta& operator= (const Motocicleta& source);

  string toString();

};                     
#endif

Proprietario.h

#ifndef __PROPRIETARIO__
#define __PROPRIETARIO__

#include <iostream>
#include "motocicleta.h"
#include "caminhao.h"
#include "carreta.h"
#include "carro.h"

using namespace std;

class Carro;
class Carreta;
class Caminhao;
class Motocicleta;

class Proprietario{
protected:
  string nome;
  string cpf;
  Motocicleta* mMoto;
  Caminhao* mCaminhao;
  Carreta* mCarreta;
  Carro* mCarro;
};

Veiculo.h:

#ifndef __VEICULO__
#define __VEICULO__
#include <iostream>
#include "proprietario.h"
#include "roda.h"
#include "motor.h"

using namespace std;
class Motor;
class Proprietario;
class Veiculo{
protected:
  int nPassageiros;
  string modelo;
  string placa;
  int aFabricacao;
  Proprietario* pai;
  Roda* rodas;
  Motor* mMotor;
  int nRodas;
  };

I removed the methods because if I added them the question would be long, sorry, the code is in PT-BR. I've seen that the problem is usually with the forward declaration. But I cannot find the problem, I have looked at so many forums, but I cannot seem to solve the problem.

Can anyone help me?

Is there any other piece of code needed?

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3 answers


In Proprietario.cpp on line 36, you do something with the Motocicleta class, not including the full class declaration first (you only have the forward declaration).



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A header declaring the class ( #include "xxx.h"

) must be included , or the class must be declared ahead ( class xxx;

). You seem to be doing both in your headers, resulting in a forward declaration after the true declaration, which is probably the cause of the stated problems.



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You have more #include

than you need. If you only want the forward declaration, there is no need to include the header file. For example, in Proprietario.h you only use pointers to Motocicleta

, Caminhao

, Carreta

and Carro

, so all you need is a cutting-edge ads, you do not need #include "motocicleta.h"

, so you can remove it.

This doesn't quite explain the error. I think if you simplify your headers it will be easier to track down the error. Without seeing proprietario.cpp and everything you removed from the headers listed in your question, I can't be sure about the reason for the error.

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