regular expression

http://www.devx.com/vb2themax/Tip/18638

Extract words with the RegExp object

The following routine extracts all the words from a source string and returns a collection. Optionally, the result contains only unique words.

This code is remarkably simpler than an equivalent "pure" VB solution because it takes advantage of the RegExp object in the Microsoft VBScript Regular Expression type library.

' Get a collection of all the words in a string

' If the second argument is True, only unique words are returned

'

'

' NOTE: requires a reference to the

'       Microsoft VBScript Regular Expression type library



Function GetWords(ByVal Text As String, Optional DiscardDups As Boolean) As _

   Collection

   Dim re As New RegExp

   Dim ma As Match

  

   ' the following pattern means that we're looking for a word character (\w)

   ' repeated one or more times (the + suffix), and that occurs on a word

   ' boundary (leading and trailing \b sequences)

   re.Pattern = "\b\w+\b"

   ' search for *all* occurrences

   re.Global = True

  

   ' initialize the result

   Set GetWords = New Collection

  

   ' we need to ignore errors, if duplicates are to be discarded

   On Error Resume Next

  

   ' the Execute method does the search and returns a MatchCollection object

   For Each ma In re.Execute(Text)

       If DiscardDups Then

           ' if duplicates are to be discarded, we just add a key to the 

           ' collection item

           ' and the Add method will do the rest

           GetWords.Add ma.Value, ma.Value

       Else

           ' otherwise just add to the result

           GetWords.Add ma.Value

       End If

   Next

  

End Function

Here is an example of how you can use the routine:

' Count how many articles appear in a source string

' held in the txtSource textbox control

Dim v As Variant

Dim count As Long



For Each v In GetWords(txtSource.Text)

   Select Case LCase$(v)

       Case "the", "a", "an"

           count = count + 1

   End Select

Next

MsgBox "Found " & count & " articles."