Visual Basic

Private Function GetCnfgParameter(ByVal MyKey As String) As String

        Dim DocXml As New XmlDocument
        Dim NodeXml As XmlNode = Nothing

        DocXml.Load(Path.Combine(Application.StartupPath, "app.xml"))

        NodeXml = DocXml.DocumentElement.SelectSingleNode("//AppDefaultValues/add[@key=""" & MyKey & """]")
        If TypeName(NodeXml.Attributes.GetNamedItem("value")) <> "Nothing" Then
            Return NodeXml.Attributes.GetNamedItem("value").Value
        Else
            Dim Message As String = String.Empty
            Message += "GetCnfgParameter:: app.con dosyasında tahrifat tespit edildi." & vbCrLf & vbCrLf
            Message += "Program kendi atamalarını kullanacaktır."

            MsgBox(Message, MsgBoxStyle.Critical)
            Return Nothing
        End If

    End Function

Private Function SaveConfigParameter(ByVal MyKey As String, ByVal MyValue As String) As Boolean

    Dim DocXml As New XmlDocument
    Dim NodeXml As XmlNode
    Dim RootXml As XmlNode
    Dim KeyXml As XmlNode
    Dim ValueXml As XmlNode

    SaveConfigParameter = False
    DocXml.Load(Path.Combine(Application.StartupPath, "app.xml"))
    NodeXml = DocXml.DocumentElement.SelectSingleNode("//AppDefaultValues/add[key=""" & MyKey & """]")

    If NodeXml Is Nothing Then
        ' The node does not exist, let's create it but nodes exist actually

        NodeXml = DocXml.CreateNode(XmlNodeType.Element, "add", "")

        ' Adding the Key attribute to the node, keep in mind, Xml tokens are case sensitive
        ' We should use 'key' instead of 'Key'

        KeyXml = DocXml.CreateNode(XmlNodeType.Attribute, "key", "")
        KeyXml.Value = MyKey
        NodeXml.Attributes.SetNamedItem(KeyXml)

        ' Adding the key value, once again, remember that Xml tokens are case sensitive

        ValueXml = DocXml.CreateNode(XmlNodeType.Attribute, "value", "")
        ValueXml.Value = MyValue
        NodeXml.Attributes.SetNamedItem(ValueXml)

        ' Add the new node to the root

        RootXml = DocXml.DocumentElement.SelectSingleNode("//AppDefaultValues")
        If Not RootXml Is Nothing Then
            RootXml.AppendChild(NodeXml)
        Else
            SaveConfigParameter = False
        End If
    Else
        '
        ' The node exist, save the new value
        '
        NodeXml.Attributes.GetNamedItem("value").Value = MyValue
        SaveConfigParameter = True
    End If
    DocXml.Save(Path.Combine(Application.StartupPath, "app.xml"))
    DocXml = Nothing

End Function