Question

我要编写一个函数来从包含初始余额的数组中提取资金。

如果余额不足，则会显示警告消息以及用户的余额。

提示用户再次输入新的金额，如果金额还可以，则提款操作已完成并且余额已更新并显示菜单。

如果余额仍然不足，将终止提款操作并显示菜单。

以下是我第一次尝试输入低于余额的金额时有效的代码。但是，如果我在第二次尝试中输入有效金额，就不能很好地更新余额。

double withdrawAmount(int pin, double balance[]){
    double amount;
    double newBalance = balance[pin];
    int withdrawTrial = 0;
    do{
        system("cls");
        cout << "-----------------------------------------" << endl;
        cout << "\tWELCOME TO EDON ATM" << endl;
        cout << "-----------------------------------------" << endl;
        cout << endl;
        cout << "Please enter amount to be withdrawn: $";
        cin >> amount;
        if (balance[pin] < amount){
            cout << endl;
            cout << "Insufficient Balance!" << endl;
            cout << "Your balance is: $" << balance[pin] << endl;
            cout << endl;
            while (withdrawTrial < 1){
                withdrawTrial++;
                cout << "Please enter amount to be withdrawn: $";
                cin >> amount;
            }
            if (withdrawTrial == 1){
                menuBoard();
                return newBalance;
            }
        }
        balance[pin] -= amount;
        newBalance = balance[pin];
    } while (amount < 0);
    return newBalance;
}

Answer 1

您没有正确按照说明进行操作。您没有在第二个提示上验证用户的输入。完全摆脱while (withdrawTrial < 1)循环。提示一次并验证。如果amount大于可用的balance，则再次提示并重新验证。如果amount仍然大于可用的balance，则退出。不需要循环（除非您要验证用户是否实际上输入了浮点数，否则就没有其他要求了。）

此外，您不应该在menuBoard()本身内部调用withdrawAmount()，而应该在withdrawAmount()退出之后调用它。

double inputDollars(const char *prompt){
    double value;

    do {
        cout << prompt << ": $";
        if (cin >> value)
            break;

        cout << endl;
        cout << "Invalid Input!" << endl;

        cin.clear();
        cin.ignore(numeric_limits<streamsize>::max(), '\n');
    }
    while (true);

    return value;
}

double withdrawAmount(int pin, double balance[]){
    double amount;

    system("cls");
    cout << "-----------------------------------------" << endl;
    cout << "\tWELCOME TO EDON ATM" << endl;
    cout << "-----------------------------------------" << endl;
    cout << endl;
    amount = inputDollars("Please enter amount to be withdrawn");

    if (balance[pin] < amount){
        cout << endl;
        cout << "Insufficient Balance!" << endl;
        cout << "Your balance is: $" << balance[pin] << endl;
        cout << endl;
        amount = inputDollars("Please enter amount to be withdrawn");

        if (balance[pin] < amount){
            cout << endl;
            cout << "Insufficient Balance!" << endl;
            return balance[pin];
        }
    }

    balance[pin] -= amount;

    return balance[pin];
}

...

double balances[N];
int pin;
...

withdrawAmount(pin, balances);
menuBoard();

从余额数组中提取金额的功能

1 个答案: