Encoding IP addresses

[Bernhard Hiller]

Some years ago, I worked at the German office of a big international hospital information system manufacturer. The server was written in MUMPS (that's really a disease...), and lots of the code were developed at the US head quarters. Some day, we had problems in the communication between computers. Eventually we found out that our American colleagues stored IP addresses in two floating point numbers and then concatenated them with a ".", something like address=float1+"."+float2 It worked fine in the US, but in Germany we use a decimal comma instead of a decimal point, and "192,168.109,47" is not a correctly formed IP address...

[adgonz]

Easy to fix. You can use the code we use at our company to convert floats between european/american decimals notation:

Function CAMBIADECIMAL(ByVal NUMERO As String, ByVal TIPO As Integer) As String
    Dim I As Integer
    Dim J As Integer

    Dim ss As String
    Dim ss1 As String
    Dim PARTE1 As String
    Dim PARTE2 As String

    Select Case TIPO
        Case 1
            ss = NUMERO
            I = ss.IndexOf(".")

            If I > 0 Then
                J = ss.Length - I - 1
                PARTE1 = ss.Substring(0, I)
                PARTE2 = ss.Substring(I + 1, J)
                ss1 = PARTE1 + "," + PARTE2
                Return (ss1)
            End If
            Return ss
        Case 2
            ss = NUMERO
            I = ss.IndexOf(",")

            If I > 0 Then
                J = ss.Length - I - 1
                PARTE1 = ss.Substring(0, I)
                PARTE2 = ss.Substring(I + 1, J)
                ss1 = PARTE1 + "." + PARTE2
                Return (ss1)
            End If
            Return ss
    End Select
End Function

[reflex codeproject]

Here in Argentina we also use comma as floating point separator, and the correct code that always works is: a) to retrieve the current decimal separator: System.Globalization.CultureInfo.CurrentCulture.NumberFormat.CurrencyDecimalSeparator b) to output ANY float using "." as its decimal separator [a float].ToString(System.Globalization.CultureInfo.InvariantCulture.NumberFormat); c) to parse using an invariant culture, with "." as decimal separator. System.Convert.ToSingle("3.1415926", System.Globalization.CultureInfo.InvariantCulture.NumberFormat);

[adgonz]

Hey, take it easy! I was just posting another horror ;P

[supercat9]

Is there any requirement that any particular octet of an IP address always be non-zero? I would think that if e.g. using a subnet mask of 255.255.254.0, an IP address of 192.168.1.0 or 192.168.0.3 would be perfectly valid.