Question

I am trying to figure out how to finish this program and get the calculations to display in the textboxes. This is what I have so far and basically the code will take the purchase price and the redemption rate and calculate the discount and interest rate. Not sure what I am doing wrong though.

Option Strict On

Public Class _Default
    Inherits System.Web.UI.Page

    Dim Purchase As Double
    Dim Redemption As Double
    Dim DiscountRate As Double
    Dim InterestRate As Double

    Protected Sub btnCalculate_Click(sender As Object, e As EventArgs) _
                                            Handles btnCalculate.Click

        Double.TryParse(txtPurchase.Text, Purchase)
        Double.TryParse(txtRedemption.Text, Redemption)
        Double.TryParse(txtDiscount.Text, DiscountRate)
        Double.TryParse(txtInterest.Text, InterestRate)

        If (CDbl(txtPurchase.Text) <= 0) Then
            MsgBox("Please enter an amount greater than 0")

        End If

        If (CDbl(txtRedemption.Text) <= 0) Then
            MsgBox("Please enter an amount greater than 0")
        End If

        DiscountRate = Purchase - Redemption / Purchase
        InterestRate = Purchase - Redemption / Redemption

    End Sub
End Class

Answer 1

They variables aren’t automatically bound to the control when you parse them. Looks like you just need to add this after your calculations:

txtDiscount.Text = DiscountRate
txtInterest.Text = InterestRate