Programmatically Selecting Files in Excel for Windows and Excel for the Mac

Sub Select_File_Or_Files_Windows()
    Dim SaveDriveDir As String
    Dim MyPath As String
    Dim Fname As Variant
    Dim N As Long
    Dim FnameInLoop As String
    Dim mybook As Workbook

    ' Save the current directory.
    SaveDriveDir = CurDir

    ' Set the path to the folder that you want to open.
    MyPath = Application.DefaultFilePath

    ' You can also use a fixed path.
    'MyPath = "C:\Users\Ron de Bruin\Test"

    ' Change drive/directory to MyPath.
    ChDrive MyPath
    ChDir MyPath

    ' Open GetOpenFilename with the file filters.
    Fname = Application.GetOpenFilename( _
            FileFilter:="Excel 97-2003 Files (*.xls), *.xls", _
            Title:="Select a file or files", _
            MultiSelect:=True)

    ' Perform some action with the files you selected.
    If IsArray(Fname) Then
        With Application
            .ScreenUpdating = False
            .EnableEvents = False
        End With

        For N = LBound(Fname) To UBound(Fname)

            ' Get only the file name and test to see if it is open.
            FnameInLoop = Right(Fname(N), Len(Fname(N)) - InStrRev(Fname(N), Application.PathSeparator, , 1))
            If bIsBookOpen(FnameInLoop) = False Then

                Set mybook = Nothing
                On Error Resume Next
                Set mybook = Workbooks.Open(Fname(N))
                On Error GoTo 0

                If Not mybook Is Nothing Then
                    MsgBox "You opened this file : " & Fname(N) & vbNewLine & _
                           "And after you press OK, it will be closed" & vbNewLine & _
                           "without saving. You can replace this line with your own code."
                    mybook.Close SaveChanges:=False
                End If
            Else
                MsgBox "We skipped this file : " & Fname(N) & " because it is already open."
            End If
        Next N
        With Application
            .ScreenUpdating = True
            .EnableEvents = True
        End With
    End If

    ' Change drive/directory back to SaveDriveDir.
    ChDrive SaveDriveDir
    ChDir SaveDriveDir
End Sub


Function bIsBookOpen(ByRef szBookName As String) As Boolean
' Contributed by Rob Bovey
    On Error Resume Next
    bIsBookOpen = Not (Application.Workbooks(szBookName) Is Nothing)
End Function

    Fname = Application.GetOpenFilename( _
            FileFilter:="XLS Files (*.xls),*.xls,CSV Files (*.csv),*.csv", _
            Title:="Select a file or files", _
            MultiSelect:=True)

Sub Select_File_Or_Files_Mac()
    Dim MyPath As String
    Dim MyScript As String
    Dim MyFiles As String
    Dim MySplit As Variant
    Dim N As Long
    Dim Fname As String
    Dim mybook As Workbook

    On Error Resume Next
    MyPath = MacScript("return (path to documents folder) as String")
    'Or use MyPath = "Macintosh HD:Users:Ron:Desktop:TestFolder:"

    ' In the following statement, change true to false in the line "multiple 
    ' selections allowed true" if you do not want to be able to select more 
    ' than one file. Additionally, if you want to filter for multiple files, change 
    ' {""com.microsoft.Excel.xls""} to 
    ' {""com.microsoft.excel.xls"",""public.comma-separated-values-text""}
    ' if you want to filter on xls and csv files, for example.
    MyScript = _
    "set applescript's text item delimiters to "","" " & vbNewLine & _
               "set theFiles to (choose file of type " & _
             " {""com.microsoft.Excel.xls""} " & _
               "with prompt ""Please select a file or files"" default location alias """ & _
               MyPath & """ multiple selections allowed true) as string" & vbNewLine & _
               "set applescript's text item delimiters to """" " & vbNewLine & _
               "return theFiles"

    MyFiles = MacScript(MyScript)
    On Error GoTo 0

    If MyFiles <> "" Then
        With Application
            .ScreenUpdating = False
            .EnableEvents = False
        End With

        MySplit = Split(MyFiles, ",")
        For N = LBound(MySplit) To UBound(MySplit)

            ' Get the file name only and test to see if it is open.
            Fname = Right(MySplit(N), Len(MySplit(N)) - InStrRev(MySplit(N), Application.PathSeparator, , 1))
            If bIsBookOpen(Fname) = False Then

                Set mybook = Nothing
                On Error Resume Next
                Set mybook = Workbooks.Open(MySplit(N))
                On Error GoTo 0

                If Not mybook Is Nothing Then
                    MsgBox "You open this file : " & MySplit(N) & vbNewLine & _
                           "And after you press OK it will be closed" & vbNewLine & _
                           "without saving, replace this line with your own code."
                    mybook.Close SaveChanges:=False
                End If
            Else
                MsgBox "We skipped this file : " & MySplit(N) & " because it Is already open."
            End If
        Next N
        With Application
            .ScreenUpdating = True
            .EnableEvents = True
        End With
    End If
End Sub

Function bIsBookOpen(ByRef szBookName As String) As Boolean
' Contributed by Rob Bovey
    On Error Resume Next
    bIsBookOpen = Not (Application.Workbooks(szBookName) Is Nothing)
End Function