using System;

using System.Globalization;

using System.Linq;

public class Program

{

    public static string FormatCurrency(string currencyCode, decimal amount)

    {

      CultureInfo culture = (from c in CultureInfo.GetCultures(CultureTypes.SpecificCultures)

                   let r = new RegionInfo(c.LCID)

                   where r != null

                   && r.ISOCurrencySymbol.ToUpper() == currencyCode.ToUpper()

                   select c).FirstOrDefault();

      if(culture == null)

      {

        // fall back to current culture if none is found

        // you could throw an exception here if that's not supposed to happen

        culture = CultureInfo.CurrentCulture; 

      }

      culture = (CultureInfo)culture.Clone();

      culture.NumberFormat.CurrencySymbol = currencyCode;

      culture.NumberFormat.CurrencyPositivePattern = culture.NumberFormat.CurrencyPositivePattern == 0 ? 2 : 3;

      var cnp = culture.NumberFormat.CurrencyNegativePattern;

      switch(cnp)

      {

       case 0: cnp = 14; break;

       case 1: cnp = 9; break;

       case 2: cnp = 12; break;

       case 3: cnp = 11; break;

       case 4: cnp = 15; break;

       case 5: cnp = 8; break;

       case 6: cnp = 13; break;

       case 7: cnp = 10; break;

      }

      culture.NumberFormat.CurrencyNegativePattern = cnp;

      return amount.ToString("C" + ((amount % 1) == 0?"0":"2"), culture);       

    }

    public static void Main()

    {

        Console.WriteLine(FormatCurrency("USD", 1230.56M));

        Console.WriteLine(FormatCurrency("USD", 1230.00M));

        Console.WriteLine(FormatCurrency("VND", 1200000M));

    }

}