How to read write and save to a config file in C#

Here you can find some c# code to read/write/save to a config file in c#.
Please note that you need to add a reference to
References -> Add Reference -> System.Configuration

 and

using System.Configuration.
In Addtion you need to add an application configuration file



Application -> Add -> New Item -> Application Configuration File
Than you need to add an <appSettings> session to it

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <appSettings>
    <add key="cnnString" value="prova"/>
    <add key="LastUpdateDate" value="10 Jan 2012"/>
  </appSettings>
</configuration>


When you run the application and debug the code you find that it is not working !! You can sse the effect when you run the exe generated in release directory.

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using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Configuration;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string cnnString;

            // Get the current configuration file.
            Configuration config =ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
            cnnString = config.AppSettings.Settings["cnnString"].Value;
            MessageBox.Show(cnnString);
            config.AppSettings.Settings["cnnString"].Value = "Cavolo";
            cnnString = config.AppSettings.Settings["cnnString"].Value;
            config.Save(ConfigurationSaveMode.Modified);
            ConfigurationManager.RefreshSection("appSettings");



        }
    }
}