Distance Calc Problems

[Bsquared]

I am building a distance calculator for an assignment. I have opted for two textboxes where the user can enter the following information: (speed limit, days planning to drive.) A list box for the user to enter the amount of hours they plan to drive on those days. I am running into some issues and going to start at the top and work my way down.

Initially the user will enter (speed limit, days driving) into the text boxes and once confirmed this will enable the button for the listbox where the user can enter the hours for driving.

How can I make the listbox recognize the number of days that has been entered into the textbox? When I run the code now I enter a number and it automatically enters that for all 7 days available.

This is what I have now. Advice always very appreciated. Thanks!

Private Sub btnCalculate_Click(sender As Object, e As EventArgs) Handles btnDistance.Click

        Dim decSpeedLimit As Decimal
        'Dim decDays As Decimal
        Dim strHours As String
        Dim decHours As Decimal
        Dim decTotalMiles As Decimal = 0

        Dim strInputMessage As String = "Enter the hours you are driving day #"
        Dim strInputHeading As String = "Daily Driving Hours"
        Dim strNormalMessage As String = "Enter the hours you are driving day #"
        Dim strNonNumericError As String = "Enter Numeric values only"
        Dim strNegativeError As String = "ERROR- Negative values are not allowed"
        Dim strTwentyError As String = "ERROR - Hours can only be between 1 and 20"

        'Loop Variables
        Dim intMaxNumberOfEntries As Integer = 7
        Dim intNumberOfEntries As Integer = 1
        Dim strCancelClicked As String = ""

        strHours = InputBox(strInputMessage & intNumberOfEntries, strInputHeading, " ")

        Do Until intNumberOfEntries > intMaxNumberOfEntries Or strHours = strCancelClicked

            If IsNumeric(strHours) Then
                decHours = Convert.ToDecimal(strHours)
                If decHours >= 1 And decHours <= 20 Then
                    lstData.Items.Add(decHours)
                    decHours += decHours
                    intNumberOfEntries += 1
                    strInputMessage = strNormalMessage
                Else
                    strInputMessage = strTwentyError
                End If
            Else
                strInputMessage = strNonNumericError
            End If
        Loop

        If intNumberOfEntries > 1 Then
            lblTotal.Visible = True
            decTotalMiles = (decSpeedLimit * decHours)
            lblTotal.Text = "Total distance traveled is " & decTotalMiles.ToString("F1") & "miles"
        Else
            MsgBox("No values entered", , "Input Error")
        End If

    End Sub

    Private Sub mnuDistance_ItemClicked(sender As Object, e As ToolStripItemClickedEventArgs) Handles mnuDistance.ItemClicked

    End Sub

    Private Sub DistanceCalculator_Load(sender As Object, e As EventArgs) Handles MyBase.Load


        lstData.Items.Clear()
        lblTotal.Text = ""
        lblTotal.Visible = False
        btnDistance.Enabled = False
        btnInfo.Enabled = True
        txtDays.Clear()
        txtSpeed.Clear()
        txtSpeed.Focus()

    End Sub

    Private Sub btnInfo_Click(sender As Object, e As EventArgs) Handles btnInfo.Click

        Dim decSpeedLimit As Decimal
        Dim decDays As Decimal

        If IsNumeric(txtSpeed.Text) Then
            decSpeedLimit = Convert.ToDecimal(txtSpeed.Text)
            If decSpeedLimit <= 0 Then
                MsgBox("Enter A Value between 25-85", , "Input Error")
                txtSpeed.Text = ""
                txtSpeed.Focus()
            End If
        Else
            MsgBox("Enter A Numeric Value", , "Input Error")
            txtSpeed.Text = ""
            txtSpeed.Focus()
        End If

        If IsNumeric(txtDays.Text) Then
            decDays = Convert.ToDecimal(txtDays.Text)
            If decDays >= 1 And decDays <= 7 Then
                decDays = decDays
                decSpeedLimit = decSpeedLimit
                btnDistance.Enabled = True
            Else
                MsgBox("Enter a value between 1-7", , "Input Error")
                txtDays.Text = ""
                txtDays.Focus()
            End If
        Else
            MsgBox("Enter a Numeric Value", , "Input Error")
            txtDays.Text = ""
            txtDays.Focus()
        End If


    End Sub

[Shaggy Hiker]

The first thing I'd do is get rid of the InputBox. I realize that you sometimes don't have a choice about using that, so you can ignore that if you must, but InputBox is almost never the right solution to any problem (I do have a single place where it was totally perfect, which is why I added the 'almost'). Creating a form that does the same thing without the problems would take only minutes, at most, so it's worth doing. The big issue with InputBox is that you can't tell the difference between cancel and no entry. That's kind of a stupid design, since you can't be sure what the user intended.

Another issue with InputBox is that it ALWAYS returns a string. That string may be a valid number, or it could be something else, including an empty string (which is indistinguishable from pressing Cancel). If you make your own input box form, you can put a label on there (to hold your caption), and a NumericUpDown control such that the user can only enter numbers where numbers are wanted. The .Value from the NUD would be a Decimal. You can leave it as such, or safely convert it to an integer. You are currently going through some contortions to convert the string from InputBox into a number, and a NUD would remove those contortions.

You should also consider using NUD in place of textboxes. The NUD is really made for numeric input, while the textbox deals only with strings.

However, if you stick with InputBox, then scrap the IsNumeric and Convert.ToDecimal() calls. You can just use Decimal.TryParse() to do both of those steps in one.

[Shaggy Hiker]

I guess I skipped over the actual question entirely in that reply.

The listbox seems like it will cause you trouble. A listbox is largely for displaying data, but you said you wanted to enter some number of hours for each day, and the listbox is not really suited for data entry. What you might consider is using a DataGridView for this. There are LOADS of options for a DGV, so it can appear a bit daunting...and you can certainly make it daunting if you want to. For example, I'd create a datatable and bind it to the DGV, which makes some things easier, but may make it appear more complicated.

Without the datatable, a DGV can act something like a spreadsheet. You could have a column for Day and a column for Hours Driven. You may want to set the AllowUserToAddRows to false (at least initially, though it might inspire you later on). If the user enters X days, then you could add X rows to the DGV, with that first column having just the numbers 1 to X. You could also make that column read only. The user would then be able to enter numbers into the other column, and you'd be able to get those numbers back out by looking at DGV.Rows(Y).Cells(X).

[Bsquared]

Yes unfortunately the list box is required on this assignment. I have not seen anything in my book about creating your own form. Can you help point me in the right direction? I am interested to look into it, if it will only take a small amount of time to help me figure this out. I'm feeling a little discouraged here. Thanks again

[ChrisE]

Hi Bsquared,

take the advice from S

here a sample with DGV, I added some sample Data, you just need to extend it to what you want

'Controls you need:
'1x ComboBox = cboJahr
'1x Datagridview = DataGridView1
'1x Button = Button1
'1 x Form = daysinYear

Option Strict On


Public Class daysinYear
    Dim ActivJahr As Long

    Sub IniCombos()
        Dim formatInfo = System.Globalization.DateTimeFormatInfo.CurrentInfo
        For i As Integer = 2010 To 2099
            cboJahr.Items.Add(i)
        Next
        cboJahr.SelectedIndex = CInt(ActivJahr - 2010)
    End Sub
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        BindData()
        FormatDataTable()
        GetData()
        DGVColumsAutoSize(True)
        Me.DataGridView1.FirstDisplayedScrollingRowIndex = Me.DataGridView1.RowCount - 1

    End Sub

    Private Sub BindData()
        DataGridView1.DataSource = GetData()
    End Sub
    Protected Function FormatDataTable() As DataTable
        Dim dt As DataTable = New DataTable()
        ' Create Columns
        dt.Columns.Add("Date", System.Type.GetType("System.String"))
        dt.Columns.Add("Week", System.Type.GetType("System.String"))
        dt.Columns.Add("Day", System.Type.GetType("System.String"))
        dt.Columns.Add("Day No.", System.Type.GetType("System.String"))
        '     dt.Columns.Add("TagKe", System.Type.GetType("System.String"))
        Return dt
    End Function

    Protected Function GetData() As DataTable
        Dim dt As DataTable = FormatDataTable()
        Dim dr As DataRow
        Dim d As Date = New Date(CInt(cboJahr.Text), 1, 1)
        Do While d.Year = CDbl(cboJahr.Text)
            Dim dateValue As Date = d
            dr = dt.NewRow
            dr("Date") = d.ToString("dd.MM.yyyy")
            dr("Week") = GetWeekfromDate(CDate(d.ToString("dd.MM.yyyy")))
            dr("Day") = d.ToString("ddd")
            dr("Day No.") = dateValue.DayOfWeek.ToString("d")
            ' dr("TagKe") = ""
            ' Add the row
            dt.Rows.Add(dr)
            d = d.AddDays(1)
        Loop
        '  ApplyFormatting()
        Return dt
    End Function

    Public Sub DGVColumsAutoSize(ByVal AutoSize As Boolean)

        If DataGridView1 Is Nothing Then
            Exit Sub
        End If

        Dim ColumnMode As DataGridViewAutoSizeColumnMode
        If AutoSize Then
            ColumnMode = DataGridViewAutoSizeColumnMode.AllCells
        Else
            ColumnMode = DataGridViewAutoSizeColumnMode.None
        End If

        With DataGridView1
            For i As Integer = 0 To .Columns.Count - 1
                .Columns(i).AutoSizeMode = ColumnMode
            Next
        End With
    End Sub

    Private Sub dayinYear_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        ActivJahr = If(ActivJahr = 0, Year(Now), ActivJahr)
        IniCombos()
    End Sub

    Function GetWeekfromDate(ByVal Datum As Date) As Byte
        Return CByte(DatePart(DateInterval.WeekOfYear, _
        Datum, FirstDayOfWeek.System, _
        FirstWeekOfYear.System))
    End Function

  
End Class

regards
Chris

[Shaggy Hiker]

If the listbox is a requirement, then you may have no choice, but....that would be a terrible constraint, because the listbox is not designed for data entry, so any solution you can come up with will suck to one extent or another. What people tend to do would be to handle the SelectedIndex changed event for the listbox, which will tell you when a person selects something, and in that event handler, move the data to a textbox, at which point you then enter something into a different textbox (or NUD), then press a button to move the information back to the listbox....where you will format it poorly, because that's about all you can do. As a solution, this is awkward and ugly, but assignments often are.

You actually already know how to create a new form, though you may have never done it explicitly, since you are given one by default in a blank project. To add a new one, go to the Project menu and select Add Windows Form. You then get a new form to play around with just as you have done with any other form. So, to make it look like an InputBox, put a label on it, a NUD, an OK button, and a CANCEL button (just buttons with their captions set). This form will be called Form2, by default, though you can change the name around.

Then, to use it, you could do something like this:

dim nf As New Form2

nf.YourLabel.Text = "Whatever text you want to show"
'You could also set the minimum and maximum for the NUD, if you wanted to.

If nf.ShowDialog = DialogResult.Ok Then
 'Get the value from the NUD:
 whateverVariable = nf.YourNUD.Value 'This will be type Decimal, even if you didn't allow decimal places.
End If

The only other thing is that in the button handler for the OK button you'd set Me.DialogResult = DialogResult.OK, and in the cancel button you'd set the dialog result to Cancel. I may have some part of the DialogResult part typed wrong, but I'm close.