C++ - Error: expected unqualified-id before ‘using’

Question

Hello, everyone.

I am having some trouble on a project I'm working on.

Here's the header file for the calor class:

#ifndef _CALOR_
#define _CALOR_

#include "gradiente.h"

using namespace std;

class Calor : public Gradiente
{
public:
    Calor();
    Calor(int a);
    ~Calor();

    int getTemp();
    int getMinTemp();
    void setTemp(int a);
    void setMinTemp(int a);

    void mostraSensor();
};
#endif

When I try to compile it:

calor.h|6|error: expected unqualified-id before ‘using’|

Why does this happen? I've been searching online and learned this error occurs mostly due to corrupted included files. Makes no sense to me, though. This class inherits from gradiente:

#ifndef _GRADIENTE_
#define _GRADIENTE_

#include "sensor.h"

using namespace std;

class Gradiente : public Sensor
{
protected:
    int vActual, vMin;
public:
    Gradiente();
    ~Gradiente();
}
#endif

Which in turn inherits from sensor

#ifndef _SENSOR_
#define _SENSOR_

#include <iostream>
#include <fstream>
#include <string>

#include "definicoes.h"

using namespace std;

class Sensor
{
protected:
    int tipo;
    int IDsensor;
    bool estadoAlerta;
    bool estadoActivo;
    static int numSensores;
public:
    Sensor(/*PARAMETROS*/);
    Sensor(ifstream &);
    ~Sensor();

    int getIDsensor();
    bool getEstadoAlerta();
    bool getEstadoActivo();

    void setEstadoAlerta(int a);
    void setEstadoActivo(int a);

    virtual void guardaSensor(ofstream &);
    virtual void mostraSensor();
    // FUNÇÃO COMUM
    /* virtual int funcaoComum() = 0;
    virtual int funcaoComum(){return 0;};*/
};
#endif

For completeness' sake, here's definicoes.h

#ifndef _DEFINICOES_
#define _DEFINICOES_

const unsigned int SENSOR_MOVIMENTO = 0;
const unsigned int SENSOR_SOM = 1;
const unsigned int SENSOR_PRESSAO = 2;
const unsigned int SENSOR_CALOR = 3;
const unsigned int SENSOR_CONTACTO = 4;

const unsigned int MIN_MOVIMENTO = 10;
const unsigned int MIN_SOM = 10;
const unsigned int MIN_PRESSAO = 10;
const unsigned int MIN_CALOR = 35;
#endif

Any help'd be much appreciated.

Thank you for your time.

Answer 1

In gradiente.h you forgot the semicolon at the end of your class declaration.

You need this:

class Gradiente : public Sensor
{
    protected:
        int vActual, vMin;
    public:
        Gradiente();
        ~Gradiente();
};  

See the added semicolon?

Answer 2

You forgot to leave the last semi colon on the closing brackets, };, on the gradiente class.

Answer 3

There is a semicolon missing at the end of this class:

class Gradiente : public Sensor
{
protected:
    int vActual, vMin;
public:
    Gradiente();
    ~Gradiente();
}

Also, the names of your include guards are illegal. Names that begin with an underscore and an uppercase letter are reserved for the C++ implementation (as are names containing a double underscore) - you are not allowed to create such names in your own code. And you should never use:

using namespace std;

in a header file. And lastly, the destructor in your Sensor base class should almost certainly be made virtual.