Interest Calculator Help

[nickTHEguitarist]

I'm making an Interest Calculator for a comp prog class and I have everything done except a monthly Interest Rate. I need to display how much you would pay a month for x amount of years and x interest for x amount of dollars. My problem is my variable for monthly interest rate has a value of zero, which messes up all my monthly total payment.

Here is my code...

Private Sub chkMonthly_Click()

'Sends Monthly Payments to lstMonthlyPayments

intCounter = 1
curPrincipal = Val(txtAmount)

lstMonthlyDisplay.AddItem ("Month" & vbTab & "Amount Payed")
dblMthInterestRate = Val(txtInterest / (12 * 100))
intMonths = (intYears * 12)

curMonthlyPayment = curPrincipal * (dblMthInterestRate / (1 - (1 + dblMthInterestRate) ^ -intMonths))

txtMonthlyPayment = Format(curMonthlyPayment, "$######.00")
txtTotalInterest = (dblMthInterestRate * intMonths)
dblMthInterestRate = Format(dblMthInterestRate, "$######.00")

For intCounter = 1 To (intYears * 12)

curTotalPayment = (curTotalPayment + curMonthlyPayment)
curTotalPayment = curTotalPayment + dblMthInterestRate
lstMonthlyDisplay.AddItem (intCounter & vbTab & Format(curTotalPayment, "$######.00"))

Next intCounter

The variable in red is the variable that has no value.

CAN ANYONE HELP.

[BruceG]

change the statement that calcs the monthly payment to:

If dblMthInterestRate = 0 Then
    curMonthlyPayment = curPrincipal / intMonths
Else
    curMonthlyPayment = curPrincipal * (dblMthInterestRate / (1 - (1 + dblMthInterestRate) ^ -intMonths))
End If

Rock on ...

[nickTHEguitarist]

curMonthlyPayment is still at value of 0...

[nickTHEguitarist]

Private Sub chkMonthly_Click()

'Sends Monthly Payments to lstMonthlyPayments

intCounter = 1
curPrincipal = Val(txtAmount)

lstMonthlyDisplay.AddItem ("Month" & vbTab & "Amount Payed")

If dblMthInterestRate = 0 Then
curMonthlyPayment = curPrincipal / intMonths
Else
curMonthlyPayment = curPrincipal * (dblMthInterestRate / (1 - (1 + dblMthInterestRate) ^ -intMonths))
End If

txtMonthlyPayment = Format(curMonthlyPayment, "$######.00")
txtTotalInterest = (dblMthInterestRate * intMonths)
dblMthInterestRate = Format(dblMthInterestRate, "$######.00")

[MartinLiss]

Are your variables defined someplace?

What is in txtAmount?

[BruceG]

Do the other textboxes still have values? Can you post the project?

[nickTHEguitarist]

yes that is just part of my code all my variables are defined and I have option explicit. txtAmount is a text box when you input the amount of money you need to pay off.

I attached my form if anyone wants to look at it and play around with it to see whats wrong. My spacing and tabbing may look bad but its the outside that should look good right

[dglienna]

Didn't you download WinZip? I told you where to get it and how to use it. It is very hard to run most programs if there is only a form. Sometimes it can be done, but only for simple forms.

[MartinLiss]

It works for me.

[nickTHEguitarist]

Yes I already had it, but I didn't know that I could turn files into zip files, I thought it was only to extract zip files. How do I turn the form into the zip file?


By the way, my form is simple

[MartinLiss]

Yes I already had it, but I didn't know that I could turn files into zip files, I thought it was only to extract zip files. How do I turn the form into the zip file?


By the way, my form is simple

You don't need to.

[Hack]

Yes I already had it, but I didn't know that I could turn files into zip files, I thought it was only to extract zip files. How do I turn the form into the zip file?


By the way, my form is simple

As someone who has difficulty balancing his own checkbook, I'm don't know much about interest calculations, but I can help you zip up a bunch of files.

Open WinZip, click on New
You will be prompted to create a new zip file. Navigate to the folder you want to create the zip file in and name it: Nick.zip

Click Ok
Now navigate to to the folder containing the files you want to put in the zip file, and, holding down the Ctrl Key, click on each file to add, then Click Add

And, there you have it!

[BruceG]

The form you posted did not have the suggested correction.

[nickTHEguitarist]

I know I forgot to save it before I sent it, but it did not work with the correction. I might have put it in wrong. Can you play with it and see if you can figure it out?

Hack,
Thanks for the zip help, where is eastpointe in Michigan?

[MartinLiss]

Here are several suggestions for you:

• Change to ListViews rather than Listboxes as the former will allow you to have headings.
• Disable the checkbox until the amount owed calculations are done
• Format total interest paid
• After the amount owed calculation is done, change lblAmountOwed.Caption to "Amount Owed after " & Val(txtYears) & " Years"

[MartinLiss]

I know I forgot to save it before I sent it, but it did not work with the correction. I might have put it in wrong. Can you play with it and see if you can figure it out?

Hack,
Thanks for the zip help, where is eastpointe in Michigan?

Did you see the image I posted?

[nickTHEguitarist]

What are ListViews? I am a beginner so I don't know too much yet.

[MartinLiss]

What are ListViews? I am a beginner so I don't know too much yet.

Hang on a bit and I'll convert one of your listboxes. Until then do you have any comment about my saying that it works for me?

[Hack]

What are ListViews? I am a beginner so I don't know too much yet.

ListView Tutorial

(Eastpointe is a suburb of Detroit...East side)

[nickTHEguitarist]

Oh I'm sorry, I didn't see your comment and your pic. Does every aspect of the program work for you, or is it just the yearly interest side? Because the yearly interest works for me also, it's the monthly interest side that doesnt work.

[BruceG]

When I put the correction in, the calc for zero interest seemed to work. Here is the corrected sub. The code in bold is the only thing I touched ...

Private Sub chkMonthly_Click()
 
    'Sends Monthly Payments to lstMonthlyPayments
    
        intCounter = 1
        curPrincipal = Val(txtAmount)
        
        lstMonthlyDisplay.AddItem ("Month" & vbTab & "Amount Payed")
        dblMthInterestRate = Val(txtInterest / (12 * 100))
        intMonths = (intYears * 12)
        [b]If dblMthInterestRate = 0 Then
            curMonthlyPayment = curPrincipal / intMonths
        Else[/b]
            curMonthlyPayment = curPrincipal * (dblMthInterestRate / (1 - (1 + dblMthInterestRate) ^ -intMonths))
        [b]End If[/b]
        txtMonthlyPayment = Format(curMonthlyPayment, "$######.00")
        txtTotalInterest = (dblMthInterestRate * intMonths)
        dblMthInterestRate = Format(dblMthInterestRate, "$######.00")
    
    For intCounter = 1 To (intYears * 12)
        
        curTotalPayment = (curTotalPayment + curMonthlyPayment)
        curTotalPayment = curTotalPayment + dblMthInterestRate
        lstMonthlyDisplay.AddItem (intCounter & vbTab & Format(curTotalPayment, "$######.00"))
    
    Next intCounter
    
       
        
    
End Sub

[nickTHEguitarist]

Mine still doesn't work, when you run the program, what are you getting for total interest paid?

[MartinLiss]

Here a project to try.

[nickTHEguitarist]

Here a project to try.

I think we have different versions of visual basic, because mine doesn't like your "columnheaders"

[MartinLiss]

Mine still doesn't work, when you run the program, what are you getting for total interest paid?

I'm getting a value but it's not correct. What your are doing is this

txtTotalInterest = (dblMthInterestRate * intMonths)

which to me looks like just a multipication of the rate rather than money paid.

[MartinLiss]

I think we have different versions of visual basic, because mine doesn't like your "columnheaders"

Are you using VB6? Did you run the project or just the form?

[nickTHEguitarist]

I'm getting a value but it's not correct. What your are doing is this

txtTotalInterest = (dblMthInterestRate * intMonths)

which to me looks like just a multipication of the rate rather than money paid.

So I should make it as txtTotalInterest =(dblMthInterestRate * intMonths + curMonthlyPayment)?

[MartinLiss]

I think one way would be

txtTotalInterest = (curMonthlyPayment * intMonths - Val(txtAmount))

which is the total amount paid minus the principle.

[nickTHEguitarist]

Ok, thanks for all your help guys. I am going to try and figure the problem in class monday with my teacher. It's easier to get help from someone standing next to you than someone who's hundreds of miles away. THANKS!

[MartinLiss]

OK. If you decide to use the ListView change the initial column width settings to

Set clmX = lvDisplay.ColumnHeaders.Add(, , "Year", 800)
   Set clmX = lvDisplay.ColumnHeaders.Add(, , "AmountOwed", 1800)

and put this at the end of cmdCalculate which will compensate for the width of the vertical scrollbar (so you don't get an horizontal one).

If lvDisplay.ListItems.Count > 6 Then
        lvDisplay.ColumnHeaders(2).Width = 1520
    End If