C++ - 错误:'using'之前的预期unqualified-id

Question

我有一个C++程序,当我尝试编译它时会出错:

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

这是calor该类的头文件:

#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

为什么会这样？

该类继承自gradiente:

#ifndef _GRADIENTE_
#define _GRADIENTE_

#include "sensor.h"

using namespace std;

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

而这又从中继承而来 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

为了完整起见,这里是 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

我究竟做错了什么？

Answer 1

在本课程结束时缺少分号:

class Gradiente : public Sensor
{
protected:
    int vActual, vMin;
public:
    Gradiente();
    ~Gradiente();
}                       // <-- semicolon needed after the right curly brace.

此外,您的包含警卫的名称是非法的.以下划线和大写字母开头的名称是为C++实现保留的(包含双下划线的名称) - 不允许在自己的代码中创建此类名称.你永远不应该使用:

using namespace std;

在头文件中.最后,传感器基类中的析构函数几乎可以肯定是虚拟的.

Answer 2

在gradiente.h中,您在类声明结束时忘记了分号.

你需要这个:

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

看到添加的分号？

Answer 3

您忘记将最后一个半冒号};留在gradiente类的右括号中。