Question

帐户是基类，检查和保存是我试图设置费率的派生类（这是一个在cheking和保存类中的方法）。我怎么能打电话给这样的方法。 Attched是代码的骨架。鉴于MY INEXPERIENCE，欢迎任何建议。

class Account {
public:
    void setAccNum(long acct) { 
    }

    void setBalance(double bal) {

    }

    string toString(){


    }


    double virtual computeIntr(int years) {

    }

};

class Checking : public Account {

public:

    Checking() {

    }
    Checking(long acct, double bal) : Account(acct, bal) {

    }
    void setMinIntrBalance(int minb) {


    }

      void  setRate(int r) {

    }


    double computeIntr(int years) {

    }




    string toString() {


    }

};

class Saving : public Account {
public:
    Saving() {

    }
    Saving(long acct, double bal, double rate) : Account(acct, bal) {



    }

    void setRate(double rate) {

    }

    double computeIntr(int years) {

    }

    string toString() {
};





int main() {

    Account **accountPtrs;
    accountPtrs = new Account*[100];

    for (int i = 0; i < 100; i++) {
        accountPtrs[i] = nullptr;
    }
    accountPtrs[0] = new Checking(100, 1000 + 1000);
    accountPtrs[1] = new Checking(101, 1000 + 1010);
    accountPtrs[2] = new Checking(102, 1000 + 1020);
    accountPtrs[3] = new Checking(103, 1000 + 1030);
    accountPtrs[4] = new Checking(104, 1000 + 1040);

    accountPtrs[5] = new Saving(200, 1000 + 2000, 3);
    accountPtrs[6] = new Saving(201, 1000 + 2010, 3);
    accountPtrs[7] = new Saving(202, 1000 + 2020, 3);
    accountPtrs[8] = new Saving(203, 1000 + 2030, 3);
    accountPtrs[9] = new Saving(204, 1000 + 2040, 3);


    bool exit = true;
    while (exit == true) {

        cout << "5) Set Interest" << endl;

        cout << " Please enter your choice: ";
        int ch;
        cin >> ch;
        cout << endl;

        switch (ch)
        {

        case 5:
        {
            bool a = true;
            while (a == true) {
                int h, b;
                char t;
                cout << "YOU WANT TO SET  THE INTEREST OF  AN ACCOUUNT." << endl;
                cout << "Saving or checking: ";
                cin >> t;

                if (t == 'c' || t == 'C') {
                    cout << "Enter account number: ";
                    cin >> h;
                    h = h - 100;
                    cout << "ENTER THE INTEREST RATE:";
                    cin >> b;

                    accountPtrs[h]->setRate();    /////// THIS IS WHERE IT DOES NOT WORK , HOW CAN I CALL SUCH METHOD AND SET THE RATE 

                    a = false;
                }

                else if (t == 's' || t == 'S') {
                    cout << "Enter account number: ";
                    cin >> h;
                    h = h - 100;
                    cout << "ENTER THE INTEREST RATE:";
                    cin >> b;

                    accountPtrs[h]-> setRate(b);
                    a = false;

                }

                else {

                    cout << "INVALID INPUT" << endl;

                    a = true;
                }

            }

            break;
        }
    }

    return 0;


}

Answer 1

您的数组成员指向Account - 对象，但Accout未提供方法setRate;只有子类才有。您需要在setRate级别提供Account，并将其实现为空或将其声明为抽象。然后，accountPtrs[h]->setRate()将变为有效并将调用相应子类的setRate - 实现：

class Account {
public:
  ...
  virtual void setRate(int) = 0;
  ... 
};

使用数组作为对象从派生类调用方法

1 个答案: