How to filter file names by date/time?

Question

I need help in filtering specific time/dates(all files are in .jpeg format) in my program's report generation (motion detection system) in which the user can view detected images from a specific point of time to another (e.g. 1:00pm - 2:00pm) then display the files in the listbox.

sample screenshot filename: pic_HHMMss_ddMMMyyyy

The system works like this. After a motion is detected by the webcam, it automatically captures an image and save it to C:\Surveillance System\Detected and generate the filename pic_HHMMss_ddMMMyyyy. So this is now the report generation form wherein the authorized person can view detected images by filtering the time/date of which when the photo is captured.

For now, I can only display all the files in the directory without any filters. Any insights or help is greatly appreciated. Thanks! :) codes:

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    ' make a reference to a directory
    Dim di As New IO.DirectoryInfo("c:\Surveillance System\Detected")
    Dim diar1 As IO.FileInfo() = di.GetFiles()
    Dim dra As IO.FileInfo

    'list the names of all files in the specified directory
    For Each dra In diar1
        ListBox1.Items.Add(dra)
    Next
End Sub

Private Sub ListBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ListBox1.SelectedIndexChanged
    PictureBox1.Image = Image.FromFile("C:\Surveillance System\Detected\" & ListBox1.Text)
End Sub

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    DateTimePicker2.Format = DateTimePickerFormat.Time
    DateTimePicker2.ShowUpDown = True
    DateTimePicker1.Format = DateTimePickerFormat.Time
    DateTimePicker1.ShowUpDown = True
End Sub

button1_click = show detected button2_click = clear items

Answer 1

There are two ways to do this. One is by the time listed as part of the file name:

Function GetFiles(ByVal FilterStart As DateTime, ByVal FilterEnd As DateTime) As IEnumerable(Of String)
    Dim culture As CultureInfo = CultureInfo.InvariantCulture
    Dim FormatString As String = "HHmmss_ddMMMyyyy"
    Return Directory.EnumerateFiles("c:\Surveillance System\Detected") _
        .Where(Function(f)
                   Dim Filedate As DateTime = DateTime.ParseExact(f.Replace("pic_", "").Replace(".jpeg", ""), FormatString, culture)
                   Return Filedate >= FilterStart AndAlso Filedate <= FilterEnd
               End Function)
End Function

---

Update:
I see you changed the picture. The format string provided here only supports original file name format used in the original picture. The new picture shows multiple conventions for the file name format. If you are really going to have multiple kinds of names for your files, you should consider using the Created Date option below, or extend this option to use the TryParseExact() overload that accepts an array of possible formats.

---

The other is to use the Created Date information from the file system:

Function GetFiles(ByVal FilterStart As DateTime, ByVal FilterEnd As DateTime) As IEnumerable(Of String)      
    Dim di As New DirectoryInfo("c:\Surveillance System\Detected")
    Return di.EnumerateFileSystemInfos() _
        .Where(Function(f) f.CreationTime >= FilterStart AndAlso f.CreationTime <= FilterEnd) _
        .Select(Function(f) f.Name)
End Function

Answer 2

Try using GetAttributes on your files

see http://msdn.microsoft.com/en-us/library/system.io.file.getattributes(v=vs.110).aspx

EDIT This will add files created between the two times you set in your DateTimePicker. This will work if you want filter on when the file was created, otherwise you need to do some text transformations to dra.FileName to match it to your filenames. You would also want to add an event to track changes in the DateTimePickers so your list will automatically filter and update

'list the names of all files in the specified directory
    For Each dra In diar1
        If dra.CreationTime > DateTimePicker1.Value And dra.CreationTime < DateTimePicker2.Value Then
            ListBox1.Items.Add(dra)
        End If
    Next

If you want use the filename then you need to the extract date and convert the text to date so you can file based on the DateTimePicker

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click


       DateTimePicker_ValueChanged(sender,Nothing)
End Sub


Private Sub DateTimePicker_ValueChanged(sender As System.Object, e As System.EventArgs) Handles  DateTimePicker1.ValueChanged, DateTimePicker2.ValueChanged


    Dim di As New IO.DirectoryInfo("c:\Surveillance System\Detected")
    Dim diar1 As IO.FileInfo() = di.GetFiles()
    Dim dra As IO.FileInfo

    ListBox1.Items.Clear()
    'list the names of all files in the specified directory
    For Each dra In diar1

        'Get file name and then convert to time
        Dim splitname As String() = Replace(dra.Name.ToString, ".jpeg", "").Split("_")
        Dim filetime As DateTime = Date.ParseExact(splitname(2) & splitname(1), "ddMMMyyyyHHmmss", System.Globalization.DateTimeFormatInfo.InvariantInfo)

        If filetime > DateTimePicker1.Value And filetime < DateTimePicker2.Value Then
            ListBox1.Items.Add(dra)

        End If
    Next

end Sub