c++ - 在 .cpp 中为派生类实现构造函数？

Question

我的问题很新手，是的，我已经广泛查阅了它，但是当我做这些事情时，我发现在线 Xcode 给我错误。

基本上，我只是好奇如何为派生类实现构造函数。我的类名为“Sensor”，派生类是 digitalSensor 和 analogSensor。

Here's my sensor.h:

    #ifndef __Program_6__sensor__
    #define __Program_6__sensor__

    #include <iostream>

    class sensor {
        char* SensorName;
        float energyDraw;
        int functioning;
        int onoff;

    public:
        sensor(char*n, float pc);
        virtual void print();

        void setOK(int K);
        int getOK();
        void setOnOff(int n);
        int getOnOff();
    };
    //---------
    class digitalSensor : public sensor {
        int reading;

    public:
        digitalSensor(char*n, float pc);
        virtual void print();
        void setCurrentReading(int r);
        int getCurrentReading();
    };

    class analogSensor : public sensor {
        int Reading;
        int minRead;
        int maxRead;

    public:
        analogSensor(char *n, float pc, int mm, int mx);
        virtual void print();
        void setCurrentReading(int r);
        int getCurrentReading();
    };


    #endif /* defined(__Program_6__sensor__) */

这是我的 sensor.cpp，您可以在底部看到我的 digitalSensor 工作的开始。

#include "sensor.h"
#include "definitions.h"
using namespace std;

//--------SENSOR CLASS------------//
sensor::sensor(char *n, float pc) {

    SensorName = (char*)malloc(strlen(n)+1);
    energyDraw = pc;
    functioning = WORKING;
    onoff = OFF;
}
void sensor::print() {
    cout << "     Sensor: " << SensorName;
    cout << "   Power Consumption: " << energyDraw;
    if (functioning == WORKING) {
        cout << "\nSensor is functioning correctly\n";

        if (onoff == ON) {
        cout << "Sensor is On";
    }
        if (onoff == OFF) {
        cout << "Sensor is Off";
    }

    }
    if (functioning == NOTWORKING) {
        cout << "Sensor is not functioning correctly";
    }
    }
void sensor::setOK(int k) {
    functioning = k;
}
int sensor::getOK() {
    return functioning;
}
void sensor::setOnOff(int n) {
    onoff = n;
}
int sensor::getOnOff() {
    return onoff;
}
//---------------------------------//

//*********DIGITAL SENSOR**********//

sensor digitalSensor::digitalSensor(char *n, float pc) {

}

简而言之:我需要为数字传感器类创建一个构造函数。我错过了什么，我该怎么做？提前感谢您提供这方面的任何帮助或知识!

Answer 1

像这样实现它的构造函数:

digitalSensor::digitalSensor(char*n, float pc) : sensor(n, pc)
{
}

如您所见，它不返回任何内容，而是调用其父级的构造函数。

但是你这样做是错误的:

sensor digitalSensor::digitalSensor(char *n, float pc) {
^^^^^^ constructors shall not return anything
}