Binaryworld - InstrTblRev - The last occurrence of a char in a table ... [ VB.net -> String ]

' If INCLUDE is True or is omitted, return the last occurrence of a character
' in a group
' or -1 if SOURCE doesn't contain any character among those listed in TABLE.
' If INCLUDE is False, return the last occurrence of the character in SOURCE
' that does not appear in TABLE.
'
' string indices are zero-based
' START = -1 searches from the end of string
' TABLE can be in the form "A-Z"

Function InstrTblRev(ByVal Start As Integer, ByVal Source As String, _
  ByVal Table As String, Optional ByVal Include As Boolean = True, _
  Optional ByVal CaseInsensitive As Boolean = False) As Integer
  ' create the regular expression
  Dim pattern As String
  If Include Then
    pattern = "[" & Table & "]"
  Else
    pattern = "[^" & Table & "]"
  End If
  ' prepare the correct regex option
  Dim options As Text.RegularExpressions.RegexOptions
  If CaseInsensitive Then
    options = Text.RegularExpressions.RegexOptions.IgnoreCase
  End If
  ' create the Regex object
  Dim re As New Text.RegularExpressions.Regex(pattern, options)

  ' adjust arguments for backward search
  Source = StrReverse(Source)
  If Start >= 0 And Start < Source.Length Then
    Start = Source.Length - Start
  Else
    Start = 0
  End If

  ' find the match
  Dim ma As Text.RegularExpressions.Match = re.Match(Source, Start)
  ' return the found index, or -1
  If ma.Success Then
    Return Source.Length - ma.Index - 1
  Else
    Return -1
  End If

End Function