Question

6. Loan Calculator The e most common types of loans are mortgage loans, which are tinance the purchase of a house, and car loans. A loan consists of four com- L1 ponents--amount, interest rate, duration, and periodic payment. The purpose values of the other three components. prograrmming project is to calculate the value of any one of the components given the We will ascurme that the duration is in months, that interest (given as a percent) i gages typically have an interest rate of about 4% and a duration o months). Car loans typically have between 3 and 5 years (36 to 60 months). monthly, and that payments are made monthly. Currently home mort- f 30 years (360 an interest rate of about 6% and a duration of Four built-in Visual Basic financial functions that perform loan calculations are as follows Pmt(interest rate / 1200, duration, -amount) gives 1200Rate(duration, monthly payment, -amount) gives the stated interest rate PV(interest rate/1200, duration, -monthly payment) gives NPer(interest rate/1200, monthly paymen the monthly payment the amount of the loan t, -amount) gives the duration of the loan in months Write a program in which the user specifies a val lue to calculate, enters the three other values, and clicks on the Calculate Value button. See Fig 5.16. Before any calcula- tions are made, the program should usea button is selected and that the values entered into the three text boxes corresponding to unselected radio buttons are valid. Function procedure to validate that a radio Annuity Check Value to Calculate Loan Calculator- Check Value to Calculate O Amount of loan O Interest rate (annual) O Duration of loan in months 36 × O Present value 1000 Interest rate per period 0025 O Number of payments60 14500 O Periodic payment 100 Future value $7626 29 Monthly payment 443.75 Calculate Value Calculate Value Clear All Values Clear All Values Possible outcome of Programming Project 6. FIGURE 5.46 FIGURE 5.47 Possible outcome of Programming Project 7

Answer 1

Screenshot

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program

Public Class frmLoanCalculator
    Private Sub btnCalculate_Click(sender As Object, e As EventArgs) Handles btnCalculate.Click

        Dim dblResult As Double
        If rdbLoanAmount.Checked Then
            If isValid(0) = True Then
                'Loan Amount Calculation
                dblResult = PV(txtInterestRate.Text / 1200, txtDuration.Text, txtMonthlyPmt.Text * -1)
                txtLoanAmount.Text = Math.Round(dblResult)
            End If
        ElseIf rdbInterestRate.Checked Then
            If isValid(1) = True Then
                'Interest Rate Calculation
                dblResult = 1200 * Rate(txtDuration.Text, txtMonthlyPmt.Text, txtLoanAmount.Text * -1)
                txtInterestRate.Text = Format(dblResult, "#.0")
            End If
        ElseIf rdbDuration.Checked Then
            If isValid(2) = True Then
                'Duration Calculation
                dblResult = NPer(txtInterestRate.Text / 1200, txtMonthlyPmt.Text, txtLoanAmount.Text * -1)
                txtDuration.Text = CInt(dblResult)
            End If
        ElseIf rdbMonthlyPmt.Checked Then
            If isValid(3) = True Then
                'Monthly Payment Calculation
                dblResult = Pmt(txtInterestRate.Text / 1200, txtDuration.Text, txtLoanAmount.Text * -1)
                txtMonthlyPmt.Text = Format(dblResult, "#.00")
            End If
        End If
    End Sub

    Private Function isValid(index As Integer) As Boolean
        Select Case index
            Case 0      'Calculation of Loan Amount
                If Len(txtInterestRate.Text) = 0 Then
                    MsgBox("Please enter the Interest Rate!!!")
                    txtInterestRate.Select()
                    Return False
                ElseIf Len(txtDuration.Text) = 0 Then
                    MsgBox("Please enter the Duration!!!")
                    txtDuration.Select()
                    Return False
                ElseIf Len(txtMonthlyPmt.Text) = 0 Then
                    MsgBox("Please enter the Monthly Payment Amount!!!")
                    txtMonthlyPmt.Select()
                    Return False
                ElseIf IsNumeric(txtInterestRate.Text) = False Then
                    MsgBox("Please enter valid Interest Rate!!!")
                    txtInterestRate.Select()
                    Return False
                ElseIf IsNumeric(txtDuration.Text) = False Then
                    MsgBox("Please enter valid Duration!!!")
                    txtDuration.Select()
                    Return False
                ElseIf IsNumeric(txtMonthlyPmt.Text) = False Then
                    MsgBox("Please enter valid Monthly Payment Amount!!!")
                    txtMonthlyPmt.Select()
                    Return False
                End If
            Case 1 'Calculation of Interest Rate
                If Len(txtLoanAmount.Text) = 0 Then
                    MsgBox("Please enter the Loan Amount!!!")
                    txtLoanAmount.Select()
                    Return False
                ElseIf Len(txtDuration.Text) = 0 Then
                    MsgBox("Please enter the Duration!!!")
                    txtDuration.Select()
                    Return False
                ElseIf Len(txtMonthlyPmt.Text) = 0 Then
                    MsgBox("Please enter the Monthly Payment Amount!!!")
                    txtMonthlyPmt.Select()
                    Return False
                ElseIf IsNumeric(txtLoanAmount.Text) = False Then
                    MsgBox("Please enter valid Loan Amount!!!")
                    txtLoanAmount.Select()
                    Return False
                ElseIf IsNumeric(txtDuration.Text) = False Then
                    MsgBox("Please enter valid Duration!!!")
                    txtDuration.Select()
                    Return False
                ElseIf IsNumeric(txtMonthlyPmt.Text) = False Then
                    MsgBox("Please enter valid Monthly Payment Amount!!!")
                    txtMonthlyPmt.Select()
                    Return False
                End If
            Case 2      'Calculation of Loan Duration
                If Len(txtLoanAmount.Text) = 0 Then
                    MsgBox("Please enter the Loan Amount!!!")
                    txtLoanAmount.Select()
                    Return False
                ElseIf Len(txtInterestRate.Text) = 0 Then
                    MsgBox("Please enter the Interest Rate!!!")
                    txtInterestRate.Select()
                    Return False
                ElseIf Len(txtMonthlyPmt.Text) = 0 Then
                    MsgBox("Please enter the Monthly Payment Amount!!!")
                    txtMonthlyPmt.Select()
                    Return False
                ElseIf IsNumeric(txtLoanAmount.Text) = False Then
                    MsgBox("Please enter valid Loan Amount!!!")
                    txtLoanAmount.Select()
                    Return False
                ElseIf IsNumeric(txtInterestRate.Text) = False Then
                    MsgBox("Please enter valid Interest Rate!!!")
                    txtInterestRate.Select()
                    Return False
                ElseIf IsNumeric(txtMonthlyPmt.Text) = False Then
                    MsgBox("Please enter valid Monthly Payment Amount!!!")
                    txtMonthlyPmt.Select()
                    Return False
                End If
            Case 3      'Calculation of Monthly Payment
                If Len(txtLoanAmount.Text) = 0 Then
                    MsgBox("Please enter the Loan Amount!!!")
                    txtLoanAmount.Select()
                    Return False
                ElseIf Len(txtInterestRate.Text) = 0 Then
                    MsgBox("Please enter the Interest Rate!!!")
                    txtInterestRate.Select()
                    Return False
                ElseIf Len(txtDuration.Text) = 0 Then
                    MsgBox("Please enter the Duration!!!")
                    txtDuration.Select()
                    Return False
                ElseIf IsNumeric(txtLoanAmount.Text) = False Then
                    MsgBox("Please enter valid Loan Amount!!!")
                    txtLoanAmount.Select()
                    Return False
                ElseIf IsNumeric(txtInterestRate.Text) = False Then
                    MsgBox("Please enter valid Interest Rate!!!")
                    txtInterestRate.Select()
                    Return False
                ElseIf IsNumeric(txtDuration.Text) = False Then
                    MsgBox("Please enter valid Duration!!!")
                    txtDuration.Select()
                    Return False
                End If
        End Select
        Return True
    End Function

    Private Sub rdbLoanAmount_CheckedChanged(sender As Object, e As EventArgs) Handles rdbLoanAmount.CheckedChanged
        'Makes Loan Amount Text box as readonly
        txtLoanAmount.ReadOnly = True
        txtInterestRate.ReadOnly = False
        txtDuration.ReadOnly = False
        txtMonthlyPmt.ReadOnly = False
        clearAll()
    End Sub

    Private Sub rdbInterestRate_CheckedChanged(sender As Object, e As EventArgs) Handles rdbInterestRate.CheckedChanged
        'Makes Interest Rate Text box as readonly
        txtLoanAmount.ReadOnly = False
        txtInterestRate.ReadOnly = True
        txtDuration.ReadOnly = False
        txtMonthlyPmt.ReadOnly = False
        clearAll()
    End Sub

    Private Sub rdbDuration_CheckedChanged(sender As Object, e As EventArgs) Handles rdbDuration.CheckedChanged
        'Makes Duration Text box as readonly
        txtLoanAmount.ReadOnly = False
        txtInterestRate.ReadOnly = False
        txtDuration.ReadOnly = True
        txtMonthlyPmt.ReadOnly = False
        clearAll()
    End Sub

    Private Sub rdbMonthlyPmt_CheckedChanged(sender As Object, e As EventArgs) Handles rdbMonthlyPmt.CheckedChanged
        'Makes Monthly Payment Amount Text box as readonly
        txtLoanAmount.ReadOnly = False
        txtInterestRate.ReadOnly = False
        txtDuration.ReadOnly = False
        txtMonthlyPmt.ReadOnly = True
        clearAll()
    End Sub

    Private Sub btnClear_Click(sender As Object, e As EventArgs) Handles btnClear.Click
        'Clears all text boxes and makes first radio button as selected
        clearAll()
        rdbLoanAmount.Checked = True
        txtInterestRate.Select()
    End Sub

    Private Sub frmLoanCalculator_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        'Select first radio as selected default
        rdbLoanAmount.Checked = True
        txtInterestRate.Select()
    End Sub
    Private Sub clearAll()
        'Clears all text boxes
        txtDuration.Text = ""
        txtInterestRate.Text = ""
        txtLoanAmount.Text = ""
        txtMonthlyPmt.Text = ""
    End Sub
End Class