problem with class and sub-class

Question

onemanclapping 0 Light Poster

15 Years Ago

hi, I'm a Computer Engineering student from Portugal in the 2ºterm.

Last class' job was for us to use class and sub-class systems, creating a info system for vehicle types.

I thought I was finished, but when I did the main file, the compiler shouted loads of errors that didn't happen before I'd written my main file.

here's the compiler shouting:

Building file: ../main.cpp
Invoking: GCC C++ Compiler
g++ -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"main.d" -MT"main.d" -o"main.o" "../main.cpp"
../main.cpp: In function ‘int main()’:
../main.cpp:21: error: cannot declare variable ‘b1’ to be of abstract type ‘Bicicleta’
../Bicicleta.h:7: note: because the following virtual functions are pure within ‘Bicicleta’:
../Veiculo.h:18: note: virtual float Veiculo::calcImposto() const
../main.cpp:29: warning: comparison between signed and unsigned integer expressions
../main.cpp:38: warning: comparison between signed and unsigned integer expressions
../Veiculo.h: In member function ‘Veiculo& Veiculo::operator=(const Veiculo&)’:
../Veiculo.h:12: instantiated from ‘void std::vector<_Tp, _Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >, const _Tp&) [with _Tp = Motorizado, _Alloc = std::allocator<Motorizado>]’
/usr/include/c++/4.2/bits/stl_vector.h:605: instantiated from ‘void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = Motorizado, _Alloc = std::allocator<Motorizado>]’
../main.cpp:33: instantiated from here
../Veiculo.h:12: error: non-static const member ‘const std::string Veiculo::marca’, can't use default assignment operator
../Veiculo.h:12: error: non-static const member ‘const int Veiculo::mes’, can't use default assignment operator
../Veiculo.h:12: error: non-static const member ‘const int Veiculo::ano’, can't use default assignment operator
../Motorizado.h: In member function ‘Motorizado& Motorizado::operator=(const Motorizado&)’:
../Motorizado.h:7: note: synthesized method ‘Veiculo& Veiculo::operator=(const Veiculo&)’ first required here
../Motorizado.h:7: error: non-static const member ‘const std::string Motorizado::combustivel’, can't use default assignment operator
../Motorizado.h:7: error: non-static const member ‘const int Motorizado::cilindrada’, can't use default assignment operator
/usr/include/c++/4.2/bits/vector.tcc: In member function ‘void std::vector<_Tp, _Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >, const _Tp&) [with _Tp = Motorizado, _Alloc = std::allocator<Motorizado>]’:
/usr/include/c++/4.2/bits/vector.tcc:256: note: synthesized method ‘Motorizado& Motorizado::operator=(const Motorizado&)’ first required here
make: *** [main.o] Error 1
make: Target `all' not remade because of errors.
Build complete for project TP2

here are the code files(also included as attachments):

main.cpp

#include "Automovel.h"
#include "Bicicleta.h"
#include "Camiao.h"
#include "Motorizado.h"
#include "Veiculo.h"
#include <iostream>
#include <vector>



using namespace std;


int main()
{
	vector<Veiculo*> v;
	
	Automovel a1("Fiat",5,1997,"gasolina",1200,5);
	Camiao c1("Ford",3,1999,"gasolina",1400,1000);
	Automovel a2("Renault",9,1997,"gasoleo",1300,5);
	Bicicleta b1("XX",4,2002,"TodoTerreno");
	
	v.push_back(&a1);
	v.push_back(&c1);
	v.push_back(&a2);
	v.push_back(&b1);
	
	cout << "vector v:"<< endl;
	for (int i=0; i<v.size(); i++)
	   v[i]->info();
	   
	vector<Motorizado> v2;
	v2.push_back(a1);
	v2.push_back(c1);
	v2.push_back(a2);
	
	cout << "vector v2:"<< endl;
	for (int i=0; i<v2.size(); i++)
	   v2[i].info();
}

Automovel.h

#ifndef AUTOMOVEL_H_
#define AUTOMOVEL_H_

#include "Motorizado.h"

class Automovel : public Motorizado
{
public:
	Automovel(string m, int mm, int aaaa, string comb, int cil, int lug);
	virtual ~Automovel();
	void info() const;
private:
	const int lugares;
};

#endif /*AUTOMOVEL_H_*/

Automovel.cpp

#include "Automovel.h"

Automovel::Automovel(string m, int mm, int aaaa, string comb, int cil, int lug)
:Motorizado(m,mm,aaaa,comb,cil),lugares(lug)
{
}

Automovel::~Automovel()
{
}

void Automovel::info() const
{
	Motorizado::info();
	cout << "Lugares: " << lugares << endl;
}

Bicicleta.h

#ifndef BICICLETA_H_
#define BICICLETA_H_

#include "Veiculo.h"

class Bicicleta : public Veiculo
{
public:
	Bicicleta(string m, int aaaa, int mm, string t);
	virtual ~Bicicleta();
	void info() const;
private:
	const string tipo;
};

#endif /*BICICLETA_H_*/

Bicicleta.cpp

#include "Bicicleta.h"

Bicicleta::Bicicleta(string m, int aaaa, int mm, string t)
:Veiculo(m,aaaa,mm),tipo(t)
{
}

Bicicleta::~Bicicleta()
{
}

void Bicicleta::info() const
{
	Veiculo::info();
	cout << "Tipo: " << tipo << cout;
}

Camiao.h

#ifndef CAMIAO_H_
#define CAMIAO_H_

#include "Motorizado.h"

class Camiao : public Motorizado
{
public:
	Camiao(string m, int mm, int aaaa, string comb, int cil, int p);
	virtual ~Camiao();
	void info() const;
private:
	const int peso;
};

#endif /*CAMIAO_H_*/

Camiao.cpp

#include "Camiao.h"

Camiao::Camiao(string m, int mm, int aaaa, string comb, int cil, int p)
:Motorizado(m,mm,aaaa,comb,cil),peso(p)
{
}

Camiao::~Camiao()
{
}

void Camiao::info() const
{
	Motorizado::info();
	cout << "Peso: " << peso << endl;
}

Motorizado.h

#ifndef MOTORIZADO_H_
#define MOTORIZADO_H_

#include "Veiculo.h"

class Motorizado : public Veiculo
{
public:
	Motorizado(string m, int mm, int aaaa, string comb, int cil);
	virtual ~Motorizado();
	void info() const;
	float calcImposto() const;
private:
	const string combustivel;
	const int cilindrada;
};

#endif /*MOTORIZADO_H_*/

Motorizado.cpp

#include "Motorizado.h"

Motorizado::Motorizado(string m, int mm, int aaaa, string comb, int cil)
:Veiculo(m,aaaa,mm),combustivel(comb),cilindrada(cil)
{
}

Motorizado::~Motorizado()
{
}

void Motorizado::info() const
{
	Veiculo::info();
	cout << "Combustivel: " << combustivel << endl;
	cout << "Cilindrada: " << cilindrada << endl;
}

float Motorizado::calcImposto() const
{
	if(ano>1995)
	{
		if((combustivel=="gasolina"&&cilindrada<=1000)||(combustivel!="gasolina"&&cilindrada<=1500))
			return 14,56;
		if((combustivel=="gasolina"&&cilindrada>1000&&cilindrada<=1300)||(combustivel!="gasolina"&&cilindrada>1500&&cilindrada<=2000))
			return 29,06;
		if((combustivel=="gasolina"&&cilindrada>1300&&cilindrada<=1750)||(combustivel!="gasolina"&&cilindrada>2000&&cilindrada<=3000))
			return 45,15;
		if((combustivel=="gasolina"&&cilindrada>1750&&cilindrada<=2600)||(combustivel!="gasolina"&&cilindrada>3000))
			return 113,98;
		if(combustivel=="gasolina"&&cilindrada>2600&&cilindrada<=3500)
			return 181,17;
		if(combustivel=="gasolina"&&cilindrada>3500)
			return 320,89;
	}
	else
	{
		if((combustivel=="gasolina"&&cilindrada<=1000)||(combustivel!="gasolina"&&cilindrada<=1500))
			return 8,10;
		if((combustivel=="gasolina"&&cilindrada>1000&&cilindrada<=1300)||(combustivel!="gasolina"&&cilindrada>1500&&cilindrada<=2000))
			return 14,56;
		if((combustivel=="gasolina"&&cilindrada>1300&&cilindrada<=1750)||(combustivel!="gasolina"&&cilindrada>2000&&cilindrada<=3000))
			return 22,65;
		if((combustivel=="gasolina"&&cilindrada>1750&&cilindrada<=2600)||(combustivel!="gasolina"&&cilindrada>3000))
			return 54,89;
		if(combustivel=="gasolina"&&cilindrada>2600&&cilindrada<=3500)
			return 87,13;
		if(combustivel=="gasolina"&&cilindrada>3500)
			return 148,37;
	}
}

Veiculo.h

#ifndef VEICULO_H_
#define VEICULO_H_

#include <string>
using std::string;

#include <iostream>
using std::cout;
using std::endl;

class Veiculo
{
public:
	Veiculo(string m, int aaaa, int mm);
	virtual ~Veiculo();
	virtual void info() const;
	bool operator < (const Veiculo &v1) const;
	virtual float calcImposto() const = 0;
	
private:
	const string marca;
	const int mes;

protected:
	const int ano;
};

#endif /*VEICULO_H_*/

Veiculo.cpp

#include "Veiculo.h"

Veiculo::Veiculo(string m, int aaaa, int mm):marca(m), ano(aaaa), mes(mm)
{
}

Veiculo::~Veiculo()
{
}

void Veiculo::info() const
{
	cout << "Marca: " << marca << endl;
	cout << "Ano:" << ano << " Mês:" << mes << endl;
}

bool Veiculo::operator < (const Veiculo &v1) const
{
	if(ano>v1.ano || (ano==v1.ano && mes>v1.mes))
		return true;
	return false;
}

thank you very much in advance and sorry for the disturb, but I think it should not be a big error ;/

c++

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Latest Post 15 Years Ago Latest Post by onemanclapping

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Ancient Dragon 5,243 Achieved Level 70

15 Years Ago

class Bicicleta must implement all pure virtual methods of its base class before it can be instiantiated. It does not do that, hence the error message. Add the function virtual float calcImposto() const; (identical to the one in Veiculo but without the =0 part) to Biciclets and it should resolve the problem.

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koteswarvijay 0 Newbie Poster · Answer 1 · 2008-10-01T18:00:58+00:00

Try this code in "Bicicleta.cpp"
float Bicicleta::calcImposto() const
{
}

and in "Bicicleta.h"
float calcImposto() const;

There entries should be there as it was defined as Virtual in the Base class and the derived class has to write the definition for the same.

This should work. Any more problems, please let me know.

onemanclapping 0 Light Poster · Answer 2 · 2008-10-02T03:52:40+00:00

class Bicicleta must implement all pure virtual methods of its base class before it can be instiantiated. It does not do that, hence the error message. Add the function virtual float calcImposto() const; (identical to the one in Veiculo but without the =0 part) to Biciclets and it should resolve the problem.

oooh! that's it! thank you very much :) it's working fine now!

best regards!

problem with class and sub-class

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