Question: (Polymorphic Banking Program Using Account Hierarchy) Develop a polymorphic banking program using the Account hierarchy created in Exercise. Create a vector of Account pointers to Savings Account and Checking Account objects. For each Account in the vector, allow the user to specify an amount of money to withdraw from the Account using member function debit and an amount of money to deposit into the Account using member function credit. As you process each Account, determine its type. If an Account is a Savings Account, calculate the amount of interest owed to the Account using member function calculate Interest, then add the interest to the account balance using member function credit. After processing an Account, print the updated account balance obtained by invoking base-class member function get Balance.

Exercise: (Account Inheritance Hierarchy) Create an inheritance hierarchy that a bank might use to represent customers' bank accounts. All customers at this bank can deposit (i.e., credit) money into their accounts and withdraw (i.e., debit) money from their accounts. More specific types of accounts also exist. Savings accounts, for instance, earn interest on the money they hold. Checking accounts, on the other hand, charge a fee per transaction (i.e., credit or debit). Create an inheritance hierarchy containing base class Account and derived classes Savings Account and Checking Account that inherit from class Account. Base class Account should include one data member of type double to represent the account balance. The class should provide a constructor that receives an initial balance and uses it to initialize the data member. The constructor should validate the initial balance to ensure that it's greater than or equal to 0.0. If not, the balance should be set to 0.0 and the constructor should display an error message, indicating that the initial balance was invalid. The class should provide three member functions. Member function credit should add an amount to the current balance. Member function debit should withdraw money from the Account and ensure that the debit amount does not exceed the Account's balance. If it does, the balance should be left unchanged and the function should print the message "Debit amount exceeded account balance." Member function get Balance should return the current balance.

Derived class Savings Account should inherit the functionality of an Account, but also include a data member of type double indicating the interest rate (percentage) assigned to the Account. Savings Account's constructor should receive the initial balance, as well as an initial value for the Savings Account's interest rate. Savings Account should provide a public member function calculate Interest that returns a double indicating the amount of interest earned by an account. Member function calculate Interest should determine this amount by multiplying the interest rate by the account balance. Derived class Checking Account should inherit from base class Account and include an additional data member of type double that represents the fee charged per transaction. Checking Account's constructor should receive the initial balance, as well as a parameter indicating a fee amount. Class Checking Account should redefine member functions credit and debit so that they subtract the fee from the account balance whenever either transaction is performed successfully. Checking Account's versions of these functions should invoke the base-class Account version to perform the updates to an account balance. Checking Account's debit function should charge a fee only if money is actually withdrawn (i.e., the debit amount does not exceed the account balance). After defining the classes in this hierarchy, write a program that creates objects of each class and tests their member functions. Add interest to the Savings Account object by first invoking its calculate Interest function, then passing the returned interest amount to the object's credit function.