Assistance with MsgBox in Program

[vbendurer]

OK, it's the newbie to programming. I have written a program to calcuate and display the montly payment and total interest paid on a loan. I have to put in a note that says if interest rate is below .06 that "Interest Rate Must Be 6% or higher." I don't have a problem with the message but after the message is displayed and I hit ok, it still calculates the amount. How do I get it to either, return to program to input new interest rate then complete program: Code is as follows:

Public Class frmLoan

    Private Sub btnAnalyze_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnAnalyze.Click

        Dim p, r, n, payment, ti As Double
        ' Set MSGbox if percentage is off
        If r < 0.06 Then
            MsgBox("Interest rate must be 6 percent or higher", MsgBoxStyle.Exclamation, "WARNING")
        Else

        End If

        'set value parameters for calculation
        p = CDbl(txtloan.Text)
        r = CDbl(txtRate.Text) / 12
        n = CDbl(txtLength.Text) ' duration of loan
        payment = (p * r) / (1 - (1 + r) ^ (-n))
        ti = (n * payment) - p


        'display results from formula calculations
        With lstResults.Items
            .Clear()
            .Add("Total monthly pay is " & (FormatCurrency(payment) & "."))
            .Add("")
            .Add("Total interest is paid is " & (FormatCurrency(ti) & "."))

        End With

    End Sub
End Class

[Paul M]

All the other code (calculations) should go under the else in the if statement. So if the amount is > 0.06 then it will calculate.

[opus]

Welcome to the forum!
If you would use the code-tags, we could read your code more easily.
You checked for r<.06 and if that's true you show the messagebox, I figure you don't want to calculate with a interest <.06, if that's true put EXIT SUB after the messagebox-line. That way the calculation will not be done. I would also suggest to put the focus on the control where the interest is set (that should be text1.text) and maybe put in a correct value as well.

[Hack]

If there is no Else condition, then you don't need it.

     If r < 0.06 Then
            MsgBox("Interest rate must be 6 percent or higher", MsgBoxStyle.Exclamation, "WARNING") 
        End If

However, in this case, I believe there will be an Else condition as stated by Hell-Lord. That would be where your alternate calculation would go.

[opus]

It should be either:

If r < 0.06 Then
            MsgBox("Interest rate must be 6 percent or higher", MsgBoxStyle.Exclamation, "WARNING") 
            Exit Sub
        End If
....
....

or

If r < 0.06 Then
            MsgBox("Interest rate must be 6 percent or higher", MsgBoxStyle.Exclamation, "WARNING") 
Else
  ......
  ......          
End If

Where " .... ...." denotes all the rest of the calculations!

[jmcilhinney]

It should be either:

If r < 0.06 Then
            MsgBox("Interest rate must be 6 percent or higher", MsgBoxStyle.Exclamation, "WARNING") 
            Exit Sub
        End If
....
....

or

If r < 0.06 Then
            MsgBox("Interest rate must be 6 percent or higher", MsgBoxStyle.Exclamation, "WARNING") 
Else
  ......
  ......          
End If

Where " .... ...." denotes all the rest of the calculations!

The second option should always be preferred.

[opus]

If you say so.

BTW Knut doesn't look that cute anymore!

[jmcilhinney]

Using an Exit Sub is creating spaghetti code, although it's not an extreme example thereof. The second option is more efficient and easier to read.

[opus]

OK, I take it, Knut!