Exercise 4

1
Exercise 4

• Introduction to C
• CIS-2320

2

• Code the C windows application to implement the
  following form

3

• Create a class called Loan which contains five
  private instance variables. These members will
  contain the principle (double) of the loan, the
  interest rate (double) of the loan, the length
  (integer) of the loan as a number of payments,
  the loans monthly payment (double), and the
  loans total interest (double).
• The class will have one private method called
  Compute() which computes the monthly payment
  using the following equation payment (P R
  ((1 R)L)) / (((1 R)L) - 1)Where
  Pprinciple, Rinterest rate for 1 month,
  LLength of loan (as number of payments). The
  symbol represents raising to apower.
• The class will have a parameterized constructor.
  This constructor will be passed the principle,
  interest rate, and length of loan when it is
  called.

4

• The class will also provide accessors/getters
  for each of the private instance variables
  principle, interest rate, and length of loan,
  monthly payment, and total interest. You can
  create Properties for the above instead, if you
  want to.
• The class will also provide mutators/setters
  for the private instance variables principle,
  interest rate, and length of loan. You can create
  Properties for the above instead, if you want to.
  Be sure to call the Compute() method to
  recalculate the monthly payment in each of these
  methods.
• The class will also implement a method called
  Amortize( ) that creates an amortization schedule
  for the loan (see next slide).. Also, this
  class is to be IO independent.

5

• Add a public method called Amortize( ) to build
  an array of strings containing the loans
  complete amortization schedule consisting of the
  following 5 formatted and fixed width columns
• payment number ( 1 to number of payments )
• beginning principle balance
• amount of the payment applied to the interest
• amount of the payment applied to the principle
• new principle balance
• Notes 1. The sum of 3 and 4 above MUST
  equal the loans monthly payment for
  every payment except the last one.
  
• 2. Accumulate the total amount of interest
  for the loan.
  

6

• The user will enter the loans principle amount,
  interest rate, and length of the loan in years
  (1). When the tab key is pressed the monthly
  payment is automatically calculated and control
  is given to the month so that the user can key in
  the month, day, and year of the first payment due
  date as shown below (2). Limit the date entered
  to the 1st thru the 28th of the month.
• 1 2
  3

Control then passes to the Display Amortization
Schedule button (3)
7

• When the user clicks the Display Amortization
  Schedule button, call the Amortize() method
  described above passing an Array object. When
  control returns, add the strings in the array to
  the list box (size the box so that it can display
  exactly the number of payments for one year) and
  add the due date for each payment.. Also display
  the total number of payments made, the total
  interest paid, and the total amount paid for the
  loan as shown below.

8

• When the user clicks the Reset Form button, clear
  all text fields and the list box so that the
  form looks like

9

• When the user starts to enter data in the Loan
  Principle box or the Interest Rate box or the
  Length of loan box immediately clear the list box
  and the total boxes.If the user changes the data
  in the Loan Principle box or the Interest Rate
  box or the Length of loan box, automatically
  recalculate the monthly payment if the other two
  boxes have data.

10

• If the loan is for more than one year the list
  box should have a scroll bar so that all payments
  can be viewed by the user as shown in the slides
  below

11

• Extra Points (4) Allow any date to be
  entered as the starting payment date and make
  sure that only valid due dates are
  displayed.

12

• Extra points (4)
• Implement the Calculate Total Interest
  button which calculates and displays the total
  interest for the loan without displaying the
  amortization schedule as shown below

Extra Extra points Add additional user frie
ndly features as you see fit to enhance the
program.