2010-04-01-how-to-tell-if-a-file-is-a-word-document.md

IsWordDocument.vb

Public Function IsWordDocument(ByVal strExtension As String) As Boolean

    ' Developed by Warren Bain on 01/04/2010
    ' Copyright (c) Thought Croft Pty Ltd
    ' All rights reserved.

    ' Verifies if the supplied file extension e.g. "doc"
    ' is recognised as one of the documents that this version
    ' of Word can natively handle.  List is constructed from the
    ' types of documents that can be filtered in the Open File dialog
    ' therefore this only works from Microsoft Word 2002 onwards.

    Const strcNoiseChars           As String = "*?."
    Const strcSeparators           As String = ";,"
    Const strcDelimiter            As String = "|"

    Static colExtensions           As Collection

    Dim fdf                        As FileDialogFilter
    Dim astrExts                   As Variant
    Dim strExts                    As String
    Dim i                          As Integer

    ' Check if we have loaded the collection yet - only done once
    If colExtensions Is Nothing Then
        Set colExtensions = New Collection
        For Each fdf In Application.FileDialog(msoFileDialogOpen).Filters
            strExts = fdf.Extensions

            ' Remove any 'noise' characters from the string
            For i = 1 To Len(strcNoiseChars)
                strExts = Replace(strExts, Mid$(strcNoiseChars, i, 1), vbNullString)
            Next i

            ' Ensure we standardise on separators used
            For i = 1 To Len(strcSeparators)
                strExts = Replace(strExts, Mid$(strcSeparators, i, 1), strcDelimiter)
            Next i

            ' Turn the current set of extensions into an array
            astrExts = Split(strExts, strcDelimiter)

            ' Add all the ones we haven't already got
            For i = LBound(astrExts) To UBound(astrExts)
                ' If already there, this will fail so ignore
                On Error Resume Next
                colExtensions.Add Trim(astrExts(i)), Trim(astrExts(i))
                On Error GoTo 0
            Next i
        Next fdf
    End If

    ' We just try and look up the file type and if it fails
    ' then it is not an intrinsically supported document
    On Error Resume Next
    strExts = colExtensions.Item(strExtension)
    IsWordDocument = (Err = 0)
End Function