ASP.Net Real-Time Currency Converter using API

I am doing with static currency (AUD-->INR)

Place a button on  _.aspx page. @ button click event do this..

protected void btnShow_Click(object sender, EventArgs e)

{

    decimal apiRate = 0;

    string firstCcode="AUD";

    string lastCcode="INR"

   decimal amount=1;

   apiRate = ExchangeRateFromAPI(amount, firstCurrencyCode, currencyCode);

    //use the apiRate;

}

private decimal ExchangeRateFromAPI(decimal amount,string firstCcode, string lastCcode)

{

try

{

    WebClient web = new WebClient();

    const string urlPattern = "http://finance.yahoo.com/d/quotes.csv?s={0}{1}=X&f=l1";

    string url = String.Format(urlPattern, firstCcode, lastCcode);

   // Get response as string

   string response = new WebClient().DownloadString(url);

   // Convert string to number

   decimal exchangeRate = decimal.Parse(response, System.Globalization.CultureInfo.InvariantCulture);

   return exchangeRate;

}

catch (Exception ex){

   return 0;

}

}