[2005] help in finding max number in listbox

[vblover5678]

hello
I have a listbox which contain grades I need to select the maximum grade.

    Private Sub maxbtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles maxbtn.Click
        Dim i As Integer
        Dim m As Integer
        m = Me.MarkList.Items.Count - 1
        Dim Max As Double

        For i = 0 To m
            Max = MarkList.Items(0)
            If Max < MarkList.Items(i) Then
                Max = MarkList.Items(i)
            End If

        Next i

        Me.MarkList.SelectedIndex = i
    End Sub

should I write Me.MarkList.SelectedIndex = i to select the index? I have an error in this step I couldn't know what is the error in my statement.

Thanks

[stanav]

You are going in the right direction, just that you didn't save the index of the item with the max value. This should do it for you.

Private Sub maxbtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles maxbtn.Click
        Dim i, indexMax As Integer
        Dim m As Integer
        m = Me.MarkList.Items.Count - 1
        Dim Max As Double
        If m > 0 Then
        Max = CDble(MarkList.Items(0))
        indexMax = 0
        For i = 1 To m
            If Max < CDble(MarkList.Items(i)) Then
                Max = CDble(MarkList.Items(i))
                indexMax = i
            End If

        Next i

        Me.MarkList.SelectedIndex = indexMax
        End If
    End Sub

[MaximilianMayrhofer]

Your code is inefficient:

Private Sub maxbtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles maxbtn.Click
    Dim _Max As Double = 0
    For i = 0 To MarkList.Items.Count - 1
        If _Max < CDbl(MarkList.Items(i)) Then 
            _Max = CDbl(MarkList.Items(i))
            MarkList.SelectedIndex = i
        End If
    Next
End Sub

[stanav]

Your code is inefficient:

Private Sub maxbtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles maxbtn.Click
    Dim _Max As Double = 0
    For i = 0 To MarkList.Items.Count - 1
        If _Max < CDbl(MarkList.Items(i)) Then 
            _Max = CDbl(MarkList.Items(i)
            MarkList.SelectedIndex = i
        End If
    Next
End Sub

You may see the selected item keeps moving down the list as the code is executed. Besides, if the listbox.selectedindexchanged event is handled, that code will cause unexpected results.

[MaximilianMayrhofer]

Haha I did that on purpose. It's fun

But anyway, if there is a SelectedIndexChanged Event, then just adjust the code slightly to look like a more compact version of yours.

[dbasnett]

        Dim tstA(ListBox1.Items.Count) As Double, max As Double = 0
        For ctr As Integer = 0 To ListBox1.Items.Count - 1
            If Not Decimal.TryParse(ListBox1.Items(ctr), tstA(ctr)) Then
                tstA(ctr) = -1 'non numeric in listbox
            End If
            If tstA(ctr) > max Then
                max = tstA(ctr) : ListBox1.SelectedIndex = ctr
            End If
        Next
        'sort the scores
        Array.Sort(tstA) 'high score is at tstA(tstA.Length - 1)
        Debug.WriteLine("HIGH SCORE is " & tstA(tstA.Length - 1))

[vblover5678]

lol very cool .. thanks everyone for helping me out and entertaining us with this problem

I need to read about functions like these CDbl where do I find them? I don't use them at all