C＃基于comboBox选择检索app.config设置

Question

I will need to modify the following C# program to read all of the three letters abbreviationthe country name from config.app and list it on winForm comboBox, and making selection from comboBox to update the lbCountry.Text and lbCurrencyRate.Text accordingly. I am new on C#, not sure how to update app.config with the following details and retrieve them base on the selection of comboBox. Hope someone can help.

Country Abbr: USA
Country Name: United States of America
Currency Rate: 1.00

Country Abbr: AUS
Country Name: Australia
Currency Rate: 0.80

Country Abbr: GBR
Country Name: United Kingdom
Currency Rate: 0.76

Country Abbr: JPN
Country Name: Japan
Currency Rate: 113.00

Following are the partial code that was originally created to retrieve one country details from app.config.

    private void Main_Load(object sender, EventArgs e)
    {
        string countryName = ConfigurationManager.AppSettings.Get("COUNTRY_NAME");
        string currencyRate = ConfigurationManager.AppSettings.Get("CURRENCY_RATE");

        lbCountry.Text = string.Format("Country Name: {0}", countryName.ToString());
        lbCurrencyRate.Text = string.Format("Currency Rate: {0}", currencyRate.ToString());

        ......
    }

App.config

    <?xml version="1.0" encoding="utf-8"?>
    <configuration>
      <appSettings>
        <add key="COUNTRY_NAME" value="United States of America" />
        <add key="CURRENCY_RATE" value="1.00" />
      </appSettings>
      ......
    </configuration>

Answer 1

As suggested by Ramankingdom it's better to store the data in an .xml file and read using the XDocument class. Or you can store data in an .csv file and read with third party library like CsvHelper.