Sorting DataGridView depending on String or Numeric content

Firstly, I am using Visual Studio 2013

Secondly, I am converting what to me is a very large project from vb6 so changing the way it is organised is not an option - it is hard enough making a direct conversion actually work (9 months so far)

So, I have a form with 4 DataGridViews on it, each with up to 10 columns. The contents of each column can vary depending on lots of factors so it may be strings or it may be numeric data stored as strings. To change this so numeric data is actually held as numeric data will mean making dozens of changes each with the likelihood of screwing it up

So, when a user clicks on the header I want to intercept the sort routine to check if the column is composed of numeric or string data. This is so that if it is numeric it sorts as:

7
8
9
77

and not as

7
77
8
9

Worst case, I suppose I could do something like:

Code:

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Private Sub GridsAll_ColumnHeaderMouseClick(sender As Object, e As System.Windows.Forms.DataGridViewCellMouseEventArgs) Handles _
  Grid1.ColumnHeaderMouseClick,
  Grid2.ColumnHeaderMouseClick,
  Grid3.ColumnHeaderMouseClick,
  Grid4.ColumnHeaderMouseClick

  ' Special sort goes here ...

End Sub

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But maybe there is an easy way - all suggestions welcomed!

If the datatype for the filed is a number then it should function this way automatically ... if not you can use the StrCmpLogicalW API to compare strings with numbers in it to do what you want:

vb Code:

Declare Unicode Function StrCmpLogicalW Lib "shlwapi.dll" (ByVal s1 As String, ByVal s2 As String) As Int32

You will also need to use this in conjunction with an IComparer

Kris

Well, I have just found a very simple way of doing this for which I claim no credit!

But first, it seems that the default mode for a DataGridView cell is "TextBox" (as you will notice if you add a column) and surprisingly if you do the following (as I have done), it allows it

Code:

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Grid1.Item(5, intRow).Value = 17.356

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Even if you have Option Strict on (which you should IMHO) but it stores it as a String (news to me but I should have realised)

Anyway, if you add the following routine, it should work like magic

Code:

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Private Sub Grid_SortCompare(sender As Object, e As DataGridViewSortCompareEventArgs) Handles _
  Grid1.SortCompare,
  Grid2.SortCompare,
  Grid3.SortCompare,
  Grid4.SortCompare

  Dim MyGrid As DataGridView

  MyGrid = DirectCast(sender, DataGridView)

  If GridColumnNumericLGH(MyGrid, e.Column.Index) = False Then
      Return
    Else
      e.SortResult = If(Cint(e.CellValue1) < CInt(e.CellValue2), -1, 1)
      e.Handled = True
  End If

End Sub

Public Function GridColumnNumericLGH(MyGrid As DataGridView, intColumn As Integer) As Boolean
  ' Written 7th November 2014

  Dim intRow As Integer

  GridColumnNumericLGH = True
  For intRow = 0 to MyGrid.RowCount - 1
    If IsNumeric(MyGrid.Item(intColumn, intRow).Value) = False Then
      GridColumnNumericLGH = False
      Exit Function
    End If
  Next

End Function

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I hope this heps somebody