listbox sorting wrong

[DebbieInFlorida]

Im in Vb.net and it took a little getting used to the new listbox property, but I got it now. I am storing self created objects that contain a key and a string. THe problem is that the key is not sorting,
The values are something like

3E-1
3E-11
3E-12
3E-2

I have tried putting it into an arraylist first, then sorting, but same order. Any ideas??
thks

[Shaggy Hiker]

What's wrong with that sorting? The sort order that you show are what you would expect for strings being sorted alphabetically. If you were expecting the sort order to be:

3E-1
3E-2
3E-11
3E-12

then you are going to have to have a custom comparator function for the sort routine to call.

[NickThissen]

The string "11" comes before the string "2", just like the string "aa" comes before the string "b". Sorting in the ListBox is done using the character values, not the number values (if there are numbers). Simply put, the ListBox looks at the characters one by one and decides that "1" comes before "2", even if there is another "1" after the first "1"! It doesn't know it's actually the number 11.

[.paul.]

which version of vb.net are you using?

what if you have 10E-1, that wouldn't sort properly either?

if you're using vb2008, you can sort your listitems with LINQ

[Shaggy Hiker]

The documentation for Listbox.Sort includes an example of overriding the Sort method to provide for custom sorting. Alternatively, you could sort the information in a list, then use AddRange to add the sorted information to the Listbox. You would then want to leave the Listbox.Sorted property set to False so that the Listbox didn't re-sort the strings.

[DebbieInFlorida]

Thank you all for so many replies. I suppose upon reflection, it is sorting properly according to text rules. In answer , 10E-1 does sort properly after 9. the problem is with the 2nd part of the field. I can sort them separately and then regroup them manually, if I must

Thanks again

[.paul.]

try this:

Dim items(ListBox2.Items.Count - 1) As String
ListBox2.Items.CopyTo(items, 0)
Array.Sort(items, New comparer2)
ListBox2.Items.Clear()
ListBox2.Items.AddRange(items)

this is the comparer class:

Public Class comparer2
    Implements IComparer
 
    Public Function Compare(ByVal x As Object, ByVal y As Object) As Integer Implements System.Collections.IComparer.Compare
        If x.ToString.Split("-"c)(0) = y.ToString.Split("-"c)(0) Then
            Return CInt(x.ToString.Split("-"c)(1)).CompareTo(CInt(y.ToString.Split("-"c)(1)))
        Else
            Return x.ToString.Split("-"c)(0).CompareTo(y.ToString.Split("-"c)(0))
        End If
    End Function
 
End Class