byte array bounds checking

[mtaylor314]

I have a website that is to read a .txt file and display it's contents in a formatted way. The problem has arised that a file may be locked and therefore it will need be readable using file.readalltext(filepath).split(vbcrlf).
I am now working on reading each file through a byte array and msdn has begun the help with that. The problem that I am having is declaring the size of the byte array. These files can range from any length from 1 word to 3 pages of information. Is there anyway of finding the length of a file in bytes without having to open it. Any help would be appreciated.

            ftpfile = Session("Local") & CategoryName & ".txt"

            Try
                'StringArray = File.ReadAllText(ftpfile).Split(vbCrLf)
                Dim oFileStream As System.IO.FileStream
                oFileStream = File.OpenRead(ftpfile)
                Dim obinReader As New BinaryReader(oFileStream)
                Dim tmp As String = ""

                'Testing another way
                '=====================================================
                Dim b(1024) As Byte
                Dim temp As UTF8Encoding = New UTF8Encoding(True)

                oFileStream.Read(b, 0, b.Length)
                tmp += temp.GetString(b)

                oFileStream.Close()
                '======================================================

                'Do Until oFileStream.Position >= oFileStream.Length - 100
                '    tmp += obinReader.ReadString() & Environment.NewLine
                'Loop
                StringArray = Split(tmp, Environment.NewLine)
...
                    For i As Integer = 2 To StringArray.Length - 1
                        If StringArray(i).Length > 1 Then
                            Table1.Rows(3).Cells(0).Text += StringArray(i) & Environment.NewLine
                        Else
                            Table1.Rows(3).Cells(0).Text += vbCrLf
                        End If
                    Next
            Catch ex As Exception
                Table1.Rows(3).Cells(0).Text += "Unable to read category file"
            End Try