Question

我想提高自己在C ++中的技能，我试图构建一个存储不同能量及其消耗的代码。一切正常，但我不明白如何计算消费量。我的问题是，当我创建指向不同能量的指针时，我在Energy类中的d_consumption被重置，并且我只有最新的能量消耗。如果可能的话，我想知道我的编码风格是否很好。

class Energy
{
private:

    double d_totalconsumption = 0.0; //count total consumption
    double d_totalbill        = 0.0; //count total bill $

public:
    Energy(){}
    virtual ~Energy(){}

    void   addConsumption(double d) { d_totalconsumption += d; }
    double totalConsumption() const { return d_totalconsumption; }
    void   addBill(double d)        { d_totalbill += d; }
    double totalBill()        const { return d_totalbill; }

    virtual void   setConsumption(double consumption) =0;
    virtual void   setBill(double billCAD)            =0;
    virtual double getConsumption()             const =0;
    virtual double getBill()                    const =0;

};

class Mazout : public Energy
{
private:

    double d_consumption = 1.e-16; // init to avoid divide by zero later
    double d_bill        = 1.e-16; // init to avoid divide by zero later

public:
    Mazout() : Energy() { }
    virtual ~Mazout(){}

    void   setConsumption(double consumption) { d_consumption = liters; Energy::addConsumption(consumption); }
    void   setBill(double billCAD)            { d_bill = billCAD; }
    double getConsumption()             const { return d_consumption; }
    double getBill()                    const { return d_bill; }

};

class NaturalGas : public Energy
{
private:

    double d_consumption = 1.e-16; //init to avoid divide by zero later
    double d_bill        = 1.e-16; //init to avoid divide by zero later

public:
    NaturalGas() : Energy() {std::cout << std::fixed;}
    virtual ~NaturalGas(){}

    void   setConsumption(double consumption) { d_consumption = consumption; Energy::addConsumption(consumption);  }
    void   setBill(double billCAD)            { d_bill = billCAD; }
    double getConsumption()             const { return d_consumption; }
    double getBill()                    const { return d_bill; }

};


int main()
{

    string input;
    stringstream inputStream;
    int choice;
    bool exit = false;

    Energy *ptrEnergy;
    vector<Energy*> energyList;

    ptrEnergy = new Mazout();

    ptrEnergy->setConsumption(26180);
    ptrEnergy->setBill(26952);

    energyList.push_back(ptrEnergy)

    ptrEnergy = new NaturalGas();

    ptrEnergy->setConsumption(34000);
    ptrEnergy->setBill(17000);

    energyList.push_back(ptrEnergy)




    // print data
    std::cout << "Consumption " << energyList(0)->getConsumption() << std::endl;
    std::cout << "Bill        " << energyList(0)->getBill()        << std::endl;

    std::cout << "Consumption " << energyList(1)->getConsumption() << std::endl;
    std::cout << "Bill        " << energyList(1)->getBill()        << std::endl;

    std::cout << "Total Consumption " << ptrEnergy()->getConsumption() << std::endl;
    std::cout << "Total Bill        " << ptrEnergy()->getBill()        << std::endl;

}

我期望这样。

Consumption 26180.0
Bill        26952.0
Consumption 34000.0
Bill        17000.0
Total Consumption 29580.0 // I have 34000.0
Total Bill        43952.0 // I have 17000.0

Answer 1

我认为您不了解的概念是类的静态变量。

静态变量是同一类中的共享变量。您使用Classname::variable在代码中引用它们。静态函数也是如此。

例如，

class A {
public:
    static int object_count;
    int x;
    A(int _x) : x(_x) {
        ++object_count;
    }
};

int A::object_count = 0;

int main(){
    A a1(8);
    cout << A::object_count << endl; // prints 1
    A a2(9);
    cout << A::object_count << endl; // prints 2
}

对于您的特定问题，您希望计算所有对象实例的总消耗/成本，因此希望计数器和函数是静态的。

class Energy
{
private:

    static double d_totalconsumption = 0.0; //count total consumption
    static double d_totalbill        = 0.0; //count total bill $

public:
    Energy(){}
    virtual ~Energy(){}

    static void   addConsumption(double d) { Energy::d_totalconsumption += d; }
    static double totalConsumption() const { return Energy::d_totalconsumption; }
    static void   addBill(double d)        { Energy::d_totalbill += d; }
    static double totalBill()        const { return Energy::d_totalbill; }

    virtual void   setConsumption(double consumption) =0;
    virtual void   setBill(double billCAD)            =0;
    virtual double getConsumption()             const =0;
    virtual double getBill()                    const =0;

};

// ...

int main()
{
// ...
    std::cout << "Total Consumption " << Energy::totalConsumption() << std::endl;
    std::cout << "Total Bill        " << Energy::totalBill()        << std::endl;
}

Answer 2

感谢Daniel的静态解决方案！我将对此进行探讨。 drescherjm，我真的没有客户，Energy与另一类具有能量的建筑相关。我可能可以将d_totalconsumption放在Building类中，但是我想将其保留在Energy类中（因为这是能源的总消耗）。但是您的观点很有趣！谢谢大家

我该如何计算基类？

2 个答案: