For...Next Loop

[jbhowell]

I'm trying to request a number, n, from 1 to 30 and one of the letters S or P. Then, depending upon whether S or P was selected, calculate the sum or product of the numbers from 1 to n. The calculations should be carried out in Funtion procedures.

[vb5prgrmr]

And what code do you have so far? Look at the Rnd function in vb's help...

[yarbrough40]

It would also be helpful if you actually asked a question.

[jbhowell]

I'm sorry my question is how do I get started. What I have so far isn't working which is no surprise. Below is what I have so far, please don't laugh, I'm new and learning but not well.

Private Sub btnCalculate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalculate.Click
        Dim num As String = ""
        For n = 1 To 30
            num = txtNumber.Text
        Next
        CalculationS(num)
        CalculationP(CDbl(num))
    End Sub
    Function CalculationS(ByVal num As String) As String
        Dim calc As Double
        Dim s As String = ""
        If s = txtLetter.Text Then
            calc = 1 + CDbl(num)
        End If
        Return CStr(calc)
    End Function
    Function CalculationP(ByVal num As Double) As Double
        Dim calc As Double
        Dim p As String = ""
        If p = txtLetter.Text Then
            calc = 1 * num
        End If
        Return calc
    End Function
End Class

Thanks,
Jennifer

[yarbrough40]

I'm still very confused by all this. Could you back up and explain a little better the whole thing. Start with what your inputs are and then what the desired outputs would be from those inputs...

for example:

I have this form "Form1" which has 2 textboxes: "txtNumber", "txtLetter". The user types a random number into txtNumber between 1 and 30 and then types either S or P into txtLetter - then presses a button. I would like for the app to take that number and do bla bla and then finally return bla to another textbox where the user can do bla.

[jbhowell]

@yarbrough40
In a form I have a text box requesting the user to input a number between 1 and 30 as well as a letter p or s. When the button is clicked, depending on if p or s was selected, it should calculate the sum or product of the number from 1 to n. I'm supposed to use functions for the calculations. I've been working on it some more and have the below but it's still not right. Thanks for any advice you might have for me.
Private Sub btnCalculate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalculate.Click
Dim num As Double
Dim calc As Double
lstAnswer.Items.Clear()
For n As Integer = 1 To 30
num = CDbl(txtNumber.Text)
Next
CalculationS(num, calc)
CalculationP(num, calc)
lstAnswer.Items.Add(num & calc)
End Sub
Function CalculationS(ByVal num As Double, ByVal calc As Double) As Double
If txtLetter.Text = "S" Then
calc = 1 + num
End If
Return calc
lstAnswer.Items.Clear()
End Function
Function CalculationP(ByVal num As Double, ByVal calc As Double) As Double
If txtLetter.Text = "P" Then
calc = 1 * num
End If
Return calc
lstAnswer.Items.Clear()
End Function

[patjones]

I see a couple of problems here.

First, you're testing for option "p" or "s" inside the functions that are supposedly going to do the calculating. Make the determination of p or s the first thing you do, and then call the appropriate function depending on the option.

Second, your For...Next loop isn't really doing anything. It's just going to execute the assignment num = CDbl(txtNumber.Text) 30 times, giving you the same result for "num" each time. The way it is now, the calculations will take place outside the loop. These are accumulating calculations which must be done the number of times the loop specifies, and therefore placed inside the loop.

Also, the loop is going to run from 1 to 30 all the time, the way you've written it...no matter what number the user inputs. If "n" is the numeric input, it seems you'd want something like

For j = 1 to n
     'Calculations in here, probably depending on 'j'...
Next

Pat

[jbhowell]

Can you help with how to format the calculations? I've changed my code to the below but the calculations are way off, they keep giving me the answer 50 no matter if p or s is selected. Thanks!

Private Sub btnCalculate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalculate.Click
Dim num As Double = CDbl(txtNumber.Text)
Dim sum, product As Double
Dim n As Double
lstAnswer.Items.Clear()
If txtLetter.Text = "S" Then
sum = CalculateS(n)
lstAnswer.Items.Add(num & sum)
ElseIf txtLetter.Text = "P" Then
product = CalculationP(n)
lstAnswer.Items.Add(num & product)
End If
End Sub
Function CalculateS(ByVal n As Double) As Double
Dim result As Double
For i As Integer = 1 To CInt(n)
result += i

Next
Return result
End Function
Function CalculationP(ByVal n As Double) As Double
Dim result As Double
For j As Integer = 1 To CInt(n)
result += j
result = n * j
Next
Return result
End Function

[patjones]

I think this is a big improvement over your previous code.

First, don't you mean to pass "num" into the respective functions? As in sum = CalculateS(num) and product = CalculationP(num).

In function CalculateS I would initialize result = 0 before going into the For loop, just as a matter of good practice.

In CalculationP, I don't think that calculation is going to give the factorial. I would initialize result = 1 before the For loop, then put only result = result*j inside the loop.

Pat

[jbhowell]

@zepphead80
That worked perfectly, thank you so much! It seems so simple which makes me feel so stupid. Thanks again!