c++ - 从同一个基类派生的两个派生类有不同的结果？

Question

两个派生类具有从同一类派生的相同逻辑但结果不同。

我有一个名为的基类account和两个来自account名为savings_accountand的类的派生类checking_account。当我制作savings_account对象时，一切正常，但是当我制作类对象时checking_account，它也会创建一个空对象account类。通过使用重载运算符 <<, cout << checking_account_object，它为我提供了checking_account_object. 但是当我使用方法时，它给了我（我创建但自动创建）get_balance的平衡。与方法类似，它将钱存入，而不是。我已经在这段代码中停留了 2 天。account_objectchecking_Account_objectaccount_objectdepositaccount_objectchecking_account_object

这是我的account课程代码：

class account
{
protected:
    string name;
    double balance;
public:
    friend ostream & operator << (ostream &out, account &bank);

    account(){
        name = "unknown";
        balance = 0.00;
    }
    account (const string &person_name, const double &person_balance){
        name = person_name;
        balance = person_balance;
    }
    bool deposit(const double &amount){
        if(amount <= 0)
            return false;
        else{
            balance += amount;
            return true;
        }
    }
    bool withdraw(const double &amount){
        if(amount <= 0 )
            return false;
        else{
            balance -= amount;
            return true;
        }
    }

    double getbalance(){
        return balance;
    }

};

ostream & operator << (ostream &out, account &bank){
    out << "The back balance of " << bank.name << " is " << bank.balance << endl;
    return out;
}

这是我的代码savings_account：

class savings_account : public account
{
protected:
    string name;
    double balance;
    double int_rate;

public:
    savings_account(){
        int_rate = 0;
        name = "unknown";
        balance = 0;
    }
    savings_account(const string &person_name, const double &person_balance, const double peronal_int_rate){
        int_rate = peronal_int_rate;
        name = person_name;
        balance = person_balance;
    }
    bool deposit(double amount){
        amount += (amount*int_rate)/100;
        return account::deposit(amount);
    }

    friend ostream & operator << (ostream &out, savings_account &bank);

};

ostream & operator << (ostream &out, savings_account &bank){
    out << "The bank balance of " << bank.name << " is " << bank.balance << endl;
    return out;
}

这是checing_account类：

class checking_account : public account{
protected:
    string name;
    double balance;
    const double fee = 1.5;

public:
    checking_account(){
        name  = "unknown";
        balance  = 0;
    }
    checking_account(const string &person_name, const double &personal_balance){
        name = person_name;
        balance = personal_balance;
    }
    bool withdraw(double amount){
        amount = amount + fee;
        return account::withdraw(amount);
    }

    friend ostream & operator << (ostream &out, checking_account &bank);
};

ostream & operator << (ostream &out, checking_account &bank){
    out << "The name of account is " << bank.name << " and current balance is " << bank.balance << endl;
    return out;
}

main()功能：

int main(){
    savings_account savings_account("tanzeel", 2000, 2);
    savings_account.deposit(1000);
    cout << savings_account.getbalance() << endl;
    savings_account.withdraw(100);
    cout << savings_account.getbalance() << endl;
    cout << savings_account;


    checking_account checking_account_object("tanzeel", 100.0);
    checking_account_object.deposit(50);;
    checking_account_object.withdraw(100);
    cout << checking_account_object.getbalance() << endl;
    cout << checking_account_object;

    return 0;
}

Savings_account运作良好。但checking_account没有给我所需的输出。我期望的输出checking_account_object是

48.5
The name of account is tanzeel and current balance is 48.5

但输出为 -51.5 账户名称为 tanzeel，当前余额为 100

标签： c++c++11