Binaryworld - Any2Dec - Convert from any numeric base to decimal ... [ VB.net -> Math ]

' convert from any base to decimal
' BASE can be in the range 2-36

Function Any2Dec(ByVal otherBaseNumber As String, ByVal base As Integer) As Long
  Dim digits As String
  Dim digitValue As Long

  ' check base
  If base < 2 Or base > 36 Then
    Throw New ArgumentException("Base must be in range 2-36")
  End If

  ' get the list of valid digits
  digits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ".Substring(0, base)

  ' convert to decimal
  Dim ch As Char
  For Each ch In otherBaseNumber.ToUpper()
    ' get the digit's value
    digitValue = digits.IndexOf(ch)
    ' error if invalid digit
    If digitValue < 0 Then
      Throw New ArgumentException("Invalid character")
    End If
    ' add to running result
    Any2Dec = Any2Dec * base + digitValue
  Next
End Function