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?

Solution 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);

Solution 2

I know you specifically asked for WinForms solution, but this might help some others. For a .NET 4.0 console application, none of these worked for me. So I used the following and it worked:

private static void UpdateSetting(string key, string value)
{
    Configuration configuration = ConfigurationManager.
        OpenExeConfiguration(Assembly.GetExecutingAssembly().Location);
    configuration.AppSettings.Settings[key].Value = value;
    configuration.Save();

    ConfigurationManager.RefreshSection("appSettings");
}

Comments

[monkey_boys]

why i cant see ConfigurationManager class

[monkey_boys]

when i open app.config it not write "x" and "this is x"

[Kris-I]

add : using System.Configuration; in the using section

[Wout]

@monkey_boys: When running e.g. a win forms application from VS, the relevant .config file to look for is: <My application>.vshost.exe.config, so if you were looking in <My application>.exe.config then you don't see any change.

[Azimuth]

@AshkanMobayenKhiabani no, it adds a new comma-separated value.