VB.NET File Splitting/Joining

'==========================
'Simple Splitting/Joining code for VB.NET
'Created and coded by master131
'==========================

'Usage:
'SplitFile("C:\test.exe", 2)
'JoinFile("C:\test.exe.001")

Private Sub JoinFile(ByVal path As String)
    If Not IO.File.Exists(path) Then
        Throw New ArgumentException("The file '" & path & "' does not exist!")
        Exit Sub
    End If

    If Not path.EndsWith(".001") Then
        Throw New ArgumentException("'" & path & "' is not a valid .001 file!")
        Exit Sub
    End If

    Dim joinList As New List(Of String)
    Dim joinIndex As Integer = 1
    Dim joinName As String = IO.Path.Combine(IO.Path.GetDirectoryName(path), IO.Path.GetFileNameWithoutExtension(path) & "." & joinIndex.ToString("D3"))
    While IO.File.Exists(joinName)
        joinName = IO.Path.Combine(IO.Path.GetDirectoryName(path), IO.Path.GetFileNameWithoutExtension(path) & "." & joinIndex.ToString("D3"))
        If IO.File.Exists(joinName) Then joinList.Add(joinName)
        joinIndex += 1
    End While

    Dim finalFile(0) As Byte
    For Each file In joinList
        Dim fileBytes() As Byte = IO.File.ReadAllBytes(file)
        Dim currentIndex As Integer = finalFile.Length - 1
        ReDim Preserve finalFile(finalFile.Length + fileBytes.Length - 1)
        For i As Integer = 0 To fileBytes.Length - 1
            finalFile(currentIndex + i) = fileBytes(i)
        Next
    Next

    IO.File.WriteAllBytes(IO.Path.Combine(IO.Path.GetDirectoryName(path), IO.Path.GetFileNameWithoutExtension(path)), finalFile)
End Sub

Private Sub SplitFile(ByVal path As String, ByVal parts As Integer)
    If Not IO.File.Exists(path) Then
        Throw New ArgumentException("The file '" & path & "' does not exist!")
        Exit Sub
    End If

    Dim fInfo As New IO.FileInfo(path)

    If parts > fInfo.Length - 1 Then
        Throw New ArgumentException("The amount of parts specified (" & parts & ") is too big!")
        Exit Sub
    End If

    Dim fileContents() As Byte = IO.File.ReadAllBytes(path)
    Dim bytesPerFile As Integer = fileContents.Length / parts
    Dim remainingBytes As Integer = fileContents.Length Mod parts
    Dim currentOffset As Integer = 0
    While currentOffset <= fileContents.Length - 1
        For i As Integer = 1 To parts
            Dim bufferLength As Integer = bytesPerFile
            If i = parts Then
                bytesPerFile += remainingBytes
                bufferLength = bytesPerFile
            End If

            Dim byteBuffer(bufferLength - 1) As Byte
            For index As Integer = 0 To bufferLength - 1
                byteBuffer(index) = fileContents(currentOffset + index)
            Next

            Dim finalPath As String = path & "." & i.ToString("D3")
            IO.File.WriteAllBytes(finalPath, byteBuffer)
            currentOffset += bytesPerFile
            If i = parts Then currentOffset = fInfo.Length
        Next
    End While
End Sub