I want to use a Function inside a sub, how is this done?

[Modulus]

I have a Private Function called GetMD5String. All this function does, is it scans for files that are being opened, and if their MD5 matches with a database, an alert is shown saying

Virus detected!

Everything works well, however, I have one issue.

I need to refresh the GetMD5String function so that my program continues to have GetMD5String monitoring the files being opened. The way I think is the most practical way of doing it, is putting my GetMD5String function into a Timer1_Tick sub so my program can check every set interval. I've tried this, but I'm getting this error:

Argument not specified for parameter 'strFilename' of 'Private Function GetMD5String(strFilename As String) As String

I get this error when I try to pass GetMD5String() into Timer1_Tick


Is there any way I can refresh GetMD5String without needing to use a Timer? Or, by using a Timer but a different way of doing so?


GetMD5String code:

Private Function GetMD5String(ByVal strFilename As String) As String
        Dim MD5 As String = GetMD5String(strFilename)
        Dim cMD5 = Security.Cryptography.MD5.Create
        Dim bytHash As Byte()
        Dim sb As New System.Text.StringBuilder
        Dim scanbox As New TextBox
        scanbox.Text = My.Computer.FileSystem.ReadAllText("viruslist.txt").ToString
        Me.OpenFileDialog1.FileName = strFilename

        Using cStream As New IO.FileStream(strFilename, IO.FileMode.Open, IO.FileAccess.Read, IO.FileShare.Read)

            bytHash = cMD5.ComputeHash(cStream)
        End Using

        For Each c In bytHash
            sb.Append(c.ToString("X2"))
        Next

        If scanbox.Text.Contains(sb.ToString) Then
            Detect.ShowDialog()
            WriteToLog("Malicious exploit detected.")
            Quarantinevb.ListBox1.Items.Add(strFilename)
        End If

        Return sb.ToString



    End Function

Thanks