give write access using C# on runtime

During r开发者_StackOverflow中文版untime i need to change the app.config file how can i do it using c#

You need to add a reference to System.Configuration to your project. Then you could use code like this to modify your executable's app.config:

// Open App.Config of executable
System.Configuration.Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
// Add an Application Setting.
config.AppSettings.Settings.Remove("LastDateFeesChecked");
config.AppSettings.Settings.Add("LastDateFeesChecked", DateTime.Now.ToShortDateString());
// Save the configuration file.
config.Save(ConfigurationSaveMode.Modified);
// Force a reload of a changed section.
ConfigurationManager.RefreshSection("appSettings");

NOTE: This code will not seem to work while debugging. You must run the code in "Release Mode" in order for this to work.

Here's a promising link on CodeProject.

Not sure but try this

set a reference using the namespace

using System.Configuration;
Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
AppSettingsSection configSection = config.AppSettings;

try {
  if (configSection != null) {
    if (configSection.IsReadOnly() == false && configSection.SectionInformation.IsLocked == false) {
      configSection.Settings("KeyName").Value = "NewValue";
    config.Save();
    }
  }
}   
catch (ConfigurationException ex) {
   MessageBox.Show(ex.Message, "Configuration Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
}

CheckHere

AH.. you do not. Your question ca nbe interpreted as "i dont ahve wrights to write it". This is normal. Application folder is not to be edited by the program or normal users. Store your non-static configuration somewhere else (CommonAppData special folder).