VB Loan Payment Calculator

Private Sub cmd_Compute_Click()
    Dim N As Integer
    Dim amt, payment, rate As Double
    
    ' Get user input
    amt = Val(Txt_loan.Text)
    rate = (Val(Txt_Int.Text) / 100) / 12  ' Convert to monthly rate
    N = Val(Txt_N.Text) * 12              ' Convert years to months
    
    ' Calculate payment
    payment = Pmt(rate, N, -amt, 0, 0)
    
    ' Display formatted result
    Lbl_payment.Caption = Format(payment, "$#,##0.00")
End Sub

Imports Microsoft.VisualBasic

Public Class LoanCalculatorForm
    Private Sub btnCalculate_Click(sender As Object, e As EventArgs) Handles btnCalculate.Click
        Dim loanAmount As Double
        Dim annualRate, monthlyRate As Double
        Dim loanTermYears, loanTermMonths As Integer
        Dim monthlyPayment As Double
        
        ' Get user input
        If Not Double.TryParse(txtLoanAmount.Text, loanAmount) Then
            MessageBox.Show("Please enter a valid loan amount")
            Return
        End If
        
        If Not Double.TryParse(txtInterestRate.Text, annualRate) Then
            MessageBox.Show("Please enter a valid interest rate")
            Return
        End If
        
        If Not Integer.TryParse(txtLoanTerm.Text, loanTermYears) Then
            MessageBox.Show("Please enter a valid loan term")
            Return
        End If
        
        ' Calculate monthly values
        monthlyRate = annualRate / 100 / 12
        loanTermMonths = loanTermYears * 12
        
        ' Calculate payment using Financial.Pmt method
        monthlyPayment = Financial.Pmt(monthlyRate, loanTermMonths, -loanAmount)
        
        ' Display result
        lblMonthlyPayment.Text = monthlyPayment.ToString("C")
        
        ' Calculate and display amortization details
        CalculateAmortization(loanAmount, monthlyRate, loanTermMonths, monthlyPayment)
    End Sub
    
    Private Sub CalculateAmortization(amount As Double, rate As Double, 
                                   periods As Integer, payment As Double)
        Dim balance As Double = amount
        Dim interest, principal As Double
        
        ' Calculate total interest and principal
        Dim totalInterest As Double = 0
        
        For period As Integer = 1 To periods
            interest = Math.Round(balance * rate, 2)
            principal = Math.Round(payment - interest, 2)
            balance = Math.Round(balance - principal, 2)
            totalInterest += interest
        Next
        
        ' Display summary
        lblTotalInterest.Text = totalInterest.ToString("C")
        lblTotalPayment.Text = (amount + totalInterest).ToString("C")
    End Sub
End Class