How to Save Configuation in app.config in C# Winforms

Question

Can someone give me an example of how to save a key/value in app.config using C# and WinForms?

Answer 1

In ASP.NET:

Configuration config = WebConfigurationManager.OpenWebConfiguration(null);
AppSettingsSection app = config.AppSettings;
app.Settings.Add("x", "this is X");
config.Save(ConfigurationSaveMode.Modified);

In WinForms:

Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
AppSettingsSection app = config.AppSettings;
app.Settings.Add("x", "this is X");
config.Save(ConfigurationSaveMode.Modified);