Only return the latest 'x' files - vb.net

Question

I have the following code
Public Function ListDirLatest(ByVal Dir As String, ByVal Amount As Integer) As DataTable
Dim dt As DataTable = ListDir(Dir)
If (dt Is Nothing) Then
Return Nothing
Else
Return dt ' This is where i would like to implement the latest x-files logic
End If
End Function
Private Function ListDir(ByVal Dir As String) As DataTable
If Directory.Exists(Dir) Then
Dim dt As DataTable = GetDT()
Dim dirinfo As New DirectoryInfo(Dir)
For Each fsi As FileSystemInfo In dirinfo.GetFileSystemInfos(".txt")
Dim dr As DataRow = dt.NewRow()
dr("FileName") = fsi.Name()
dr("FileDate") = fsi.CreationTime()
Next
Return dt
Else
Return Nothing
End If
End Function
Private Function GetDT() As DataTable
'Create DataTable to hold results
Dim dt As New DataTable("DirList")
Dim st As System.Type = System.Type.GetType("System.String")
dt.Columns.Add("FileName", st)
dt.Columns.Add("FileDate", st)
Return dt
End Function
At the moment the ListDirLatest Function will return all the files the in the directory.
How do I change the code so that it only returns the latest 'x' files, as specified by the Amount argument.
To Clarify I want to return the LATEST 'x' files in the directory.

Answer 1

You can solve your problem with a little of Linq and a the reference to System.Data.DataSetExtensions
( http://msdn.microsoft.com/en-us/library/system.data.datatableextensions(v=vs.100).aspx )
Public Function ListDirLatest(ByVal Dir As String, ByVal Amount As Integer) As DataTable
Dim dt As DataTable = ListDir(Dir)
If (dt Is Nothing) Then
Return Nothing
Else
Dim r = from myRow in dt.AsEnumerable()
Order By("FileDate DESC")
Take(Amount)
dt = r.CopyToDataTable()
return dt
End If
End Function
Also, the ListDir function has a couple of errors
Add the row information to the DataTable returned
Use a correct pattern for GetFileSystemInfos
Function ListDir(ByVal Dir As String) As DataTable
If Directory.Exists(Dir) Then
Dim dt As DataTable = GetDT()
Dim dirinfo As New DirectoryInfo(Dir)
For Each fsi As FileSystemInfo In dirinfo.GetFileSystemInfos("*.txt")
Dim dr As DataRow = dt.NewRow()
dr("FileName") = fsi.Name()
dr("FileDate") = fsi.CreationTime()
dt.Rows.Add(dr)
Next
Return dt
Else
Return Nothing
End If
End Function

Answer 2

If you mean by Amount the number of files to be returned, then here is what you need to do:
First Change the header of ListDir function to accept a parameter to allow counting the number of files to be returned, and pass that parameter from the first function,
Public Function ListDirLatest(ByVal Dir As String, ByVal Amount As Integer) As DataTable
Dim dt As DataTable = ListDir(Dir, Amount)
If (dt Is Nothing) Then
Return Nothing
Else
Return dt ' This is where i would like to implement the latest x-files logic
End If
End Function
Private Function ListDir(ByVal Dir As String, ByVal Amount As Integer) As DataTable
If Directory.Exists(Dir) Then
Dim dt As DataTable = GetDT()
Dim dirinfo As New DirectoryInfo(Dir)
Dim cnt as Integer = 0
For Each fsi As FileSystemInfo In dirinfo.GetFileSystemInfos(".txt")
Dim dr As DataRow = dt.NewRow()
dr("FileName") = fsi.Name()
dr("FileDate") = fsi.CreationTime()
cnt += 1
if cnt >= Amount Then Exit For
Next
Return dt
Else
Return Nothing
End If
End Function