使用数组作为对象从派生类中调用方法

问题描述：

Account是基类，并且检查和保存是派生类我试图设置速率（这是cheking和saving类中的方法）。我怎样才能调用这样的方法。 Attched是代码的骨架。欢迎任何建议，因为我的不实。使用数组作为对象从派生类中调用方法

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; 


}

为什么'Checking'从'Account'获得？你真的想要表达像'Checking' **是一个**'Account'这样的语义吗？ – user0042

答

你的阵列成员是指向Account -objects，但Accout不提供方法setRate;只有子类才行。您需要在Account级别提供setRate，并将其实现为空或声明为抽象。然后，accountPtrs[h]->setRate()将会是有效的，并调用相应的子类的setRate -implementations：

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

还有一个问题：如果我想要一种方法让我添加一个帐户（检查或保存），我知道我可以使用新的关键词，但是如何确保新帐户（检查或保存）是存储在帐户[100]数组中？ – LondonSquare

使用数组作为对象从派生类中调用方法

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