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Determine the datatype of the columns to sort in a listview

Posted on 2004-10-31
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Last Modified: 2010-04-23
Hi,

How can you determine the datatype of the column of a listview so you can sort it properly e.g, if its numeric, string or date.

I am doing a sort on a listview and it always treat the column as string, that's why it doesn't sort properly on numeric values.

Thanks.
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Question by:MsFox
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by:
prakash_prk earned 120 total points
ID: 12463181
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemwindowsformslistviewclasslistviewitemsortertopic.asp
--------------------------------------------
Public Class ListViewSorter
    Implements IComparer
    Private mNumeric As Boolean, mDate As Boolean, ClickedColumn As Integer, isAscending As Boolean = True

    Public Sub New(ByRef ListView As System.Windows.Forms.ListView, ByVal ivlClickedColumn As Integer, ByVal bvlisAscending As Boolean)
        ClickedColumn = ivlClickedColumn
        isAscending = bvlisAscending
        mNumeric = False
        mDate = False
        If ListView.Items.Count > 0 Then
            If Microsoft.VisualBasic.IsNumeric(ListView.Items(0).SubItems(ClickedColumn).Text.ToUpper.Trim) Then
                mNumeric = True
            ElseIf Microsoft.VisualBasic.IsDate(ListView.Items(0).SubItems(ClickedColumn).Text.ToUpper.Trim) Then
                mDate = True
            End If
        End If
    End Sub

    Private Function Compare(ByVal x As Object, ByVal y As Object) As Integer Implements System.Collections.IComparer.Compare
        Try
            Dim lv1 As ListViewItem = x
            Dim lv2 As ListViewItem = y
            If mNumeric Then
                If isAscending = True Then
                    Return CDbl(lv1.SubItems(ClickedColumn).Text) + CDbl(lv2.SubItems(ClickedColumn).Text)
                Else
                    Return CDbl(lv1.SubItems(ClickedColumn).Text) - CDbl(lv2.SubItems(ClickedColumn).Text)
                End If
            ElseIf mNumeric = False And mDate = False Then
                If isAscending = True Then
                    Return String.Compare(lv2.SubItems(ClickedColumn).Text, lv1.SubItems(ClickedColumn).Text)
                Else
                    Return String.Compare(lv1.SubItems(ClickedColumn).Text, lv2.SubItems(ClickedColumn).Text)
                End If
            Else
                If isAscending = True Then
                    Return Date.Compare(CDate(Microsoft.VisualBasic.FormatDateTime(lv2.SubItems(ClickedColumn).Text, Microsoft.VisualBasic.DateFormat.LongDate)), CDate(Microsoft.VisualBasic.FormatDateTime(lv1.SubItems(ClickedColumn).Text, Microsoft.VisualBasic.DateFormat.LongDate)))
                Else
                    Return Date.Compare(CDate(Microsoft.VisualBasic.FormatDateTime(lv1.SubItems(ClickedColumn).Text, Microsoft.VisualBasic.DateFormat.LongDate)), CDate(Microsoft.VisualBasic.FormatDateTime(lv2.SubItems(ClickedColumn).Text, Microsoft.VisualBasic.DateFormat.LongDate)))
                End If
            End If
        Catch ex As Exception
            msgbox(ex.tostring)
        End Try
    End Function
End Class
------------------
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by:MsFox
ID: 12468060
Thanks.  Exactly what I needed.
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