public void EditCarsXml()
        {
            var appConfigFilePath       = string.Concat(Assembly.GetExecutingAssembly().Location, ".config");
            var appConfigWriterSettings =
                new ConfigModificatorSettings("//appSettings", "//add[@key='{0}']", appConfigFilePath);

            var value = ConfigurationManager.AppSettings["testKey1"];

            Console.WriteLine("Value before modification: {0}", value);

            ConfigModificator.ChangeValueByKey(
                key: "testKey1",
                value: "ChangedValueByModificator",
                attributeForChange: "value",
                configWriterSettings: appConfigWriterSettings);

            ConfigModificator.RefreshAppSettings();
            value = ConfigurationManager.AppSettings["testKey1"];
            Console.WriteLine("Value after modification: {0}", value);

            //Example how to change Custom XML configuration
            var carsConfigFilePath       = "Cars.xml";
            var carsConfigWriterSettings =
                new ConfigModificatorSettings("//cars", "//car[@name='{0}']", carsConfigFilePath);

            ConfigModificator.ChangeValueByKey(
                key: "BMW",
                value: "Mazda",
                attributeForChange: "name",
                configWriterSettings: carsConfigWriterSettings);
        }
        public static void ChangeValueByKey(string key, string value, string attributeForChange, ConfigModificatorSettings configWriterSettings)
        {
            XmlDocument doc      = ConfigModificator.LoadConfigDocument(configWriterSettings.ConfigPath);
            XmlNode     rootNode = doc.SelectSingleNode(configWriterSettings.RootNode);

            if (rootNode == null)
            {
                throw new InvalidOperationException("the root node section not found in config file.");
            }
            try
            {
                XmlElement elem = (XmlElement)rootNode.SelectSingleNode(string.Format(configWriterSettings.NodeForEdit, key));
                elem.SetAttribute(attributeForChange, value);
                doc.Save(configWriterSettings.ConfigPath);
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }