Loops and functions in Visual Basic?

Question

ok, i have a project that im working on and i cant seem to get it to function. the program runs, but instead of displaying the rate like i need it only shows the words. Here is my code. and the instruction for the program. Ive spent 2 weeks working on this and still cant figure it out. 

Write a program to solve the following problem: A TV set is purchased with a loan of $563 to be paid off with 5 monthly payments of $116. The interest rate is 1 percent per month. Display a table giving the balance on the loan at the end of each month.
Public Class Form1
    Private Sub btnDisplay_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDisplay.Click
        Dim month As Integer = 1
        month = 1
        Do Until month = 5 'Repeat loop until month is 5
            If month > 5 Then Exit Do ' if month is greater than 5 end the loop cycle
            month += 1
            DisplayTtl(563)
            Dim fmtStr As String = "{0,12}      {1, 4:c2}"
            ListBox1.Items.Clear()
            ListBox1.Items.Add(String.Format(fmtStr, "Month", "Rate"))
            ListBox1.Items.Add(String.Format(fmtStr, "month", "rate"))
 'KNOW this is the problem line, just not sure what it should be instead to make it display the ascending months and descending rate
        Loop
'No end if statement needed because no if statement used above
    End Sub

    Private Function DisplayTtl(ByVal balance As Double) As Double
        Dim rate As Double
        'Show rate as the balance with interest less monthly amount
        rate = (balance * 0.01) - 116
        Return rate
    End Function
End Class

ujg · Accepted Answer

Try this code out:
======Current Code Edit
Public Class Form1
Private Sub btnDisplay_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDisplay.Click
Dim month As Integer
Dim balance As Double = 563
Dim rate As Double
month = 1
Dim fmtStr As String = "{0,12} {1, 4:c2}"
ListBox1.Items.Clear()
ListBox1.Items.Add(String.Format(fmtStr, "Month", "Rate"))
ListBox1.Items.Add(String.Format(fmtStr, month, DisplayTtl(balance)))

Do Until month = 5
If month > 5 Then Exit Do
month += 1
balance = DisplayTtl(balance)
ListBox1.Items.Add(String.Format(fmtStr, month, balance))
Loop
End Sub

Private Function DisplayTtl(ByVal balance As Double) As Double
Dim rate As Double
rate = (balance * 1.01) - 116
Return rate
End Function
End Class

=======End of current code edit

Instead of making month = 0, I would recommend keeping it as month = 1 and moving month += 1 just above the line 'Loop'.  With month +=1 at the top of the loop statement, you are adding 1 to month before doing anything with it.  It is better to add 1 to month at the end of the loop statement.

Also, your function call DisplayTtl(563) will always return the same value because it is being fed the same number (563) each time it is called.  Instead, create a variable for the starting value and assign it the value 563:

Dim StartValue As Double = 563

Then use that variable in the function call:
ListBox1.Items.Add(String.Format (fmtStr, month, DisplayTtl(StartValue) )) 

Then make sure to assign the new value to StartValue in the DisplayTtl function:
Private Function DisplayTtl(ByVal balance As Double) As Double
Dim rate As Double
rate = (balance * 0.01) - 116
StartValue = rate
Return rate
End Function
End Class

For the last issue:
change
rate=(balance * 0.01) - 116
to:
rate = (balance * 1.01) - 116

Reason:
rate = (current balance + interest on balance) - payment
and
interest on balance = current balance * .01 so

rate = (current balance + currentbalance * .01) - payment
rate = (current balance * (1 + .01)) - payment
rate = (current balance * 1.01) - payment

Is the -116 still in the rate equation?

Hooray! Have a good night! :)

Anonymous · Answer

Try this code, I've modified some parts of your code:

Public Class Form1
Private Sub btnDisplay_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDisplay.Click
Dim month As Integer
Dim balance As Double
Dim rate As Double
balance = 563
month = 1

'table initialization
Dim fmtStr As String = "{0,12} {1, 4:c2}"
ListBox1.Items.Clear()
ListBox1.Items.Add(String.Format (fmtStr, "Month", "Rate") )
ListBox1.Items.Add(String.Format (fmtStr, month, balance))

Do Until month = 5
If month > 5 Then Exit Do
month += 1
rate = DisplayTtl(balance)
balance = balance + rate - 116
ListBox1.Items.Add(String.Format (fmtStr, month, balance))
Loop
End Sub

Private Function DisplayTtl(ByVal balance As Double) As Double
Dim rate As Double
rate = (balance * 0.01)
Return rate
End Function
End Class

I think this should solve your problem.
See if it works. If it doesn't, please let me know.

Hope this helps :)

---

Anonymous · Answer

attempt this code, i have changed some elements of your code: Public classification Form1 deepest Sub btnDisplay_Click(ByVal sender As equipment.merchandise, ByVal e As equipment.EventArgs) Handles btnDisplay.click Dim month As Integer Dim stability As Double Dim fee As Double stability = 563 month = a million 'table initialization Dim fmtStr As String = "{0,12} {a million, 4:c2}" ListBox1.products.clean() ListBox1.products.upload(String.format (fmtStr, "Month", "fee") ) ListBox1.products.upload(String.format (fmtStr, month, stability)) Do until eventually month = 5 If month > 5 Then go out Do month += a million fee = DisplayTtl(stability) stability = stability + fee - 116 ListBox1.products.upload(String.format (fmtStr, month, stability)) Loop end Sub deepest function DisplayTtl(ByVal stability As Double) As Double Dim fee As Double fee = (stability * 0.01) go back fee end function end classification i imagine this may clean up your problem. See if it particularly works. If it would not, please enable me recognize. wish this facilitates :) ---

Loops and functions in Visual Basic?

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