Quick and Dirty Currency Formatting in C#

A project I have been working on recently stores amounts of money along with the currency they are in. I was getting sick of the old amount + currency_code style of display and decided to see if I could hack together something that looks a bit nicer. Turns out you can use the built in .NET culture info and string.Format to format decimals into any currency.

The code queries the cultures using linq to find a culture matching the given currency code it then uses passes the culture into string.Format and asks it to format as currency (“C”). I wrapped it all up in an extension method and added a default return if the culture is not found. The code seems to work fine but I can’t really vouch for its performance or coverage of currencies other than to say “it works on my machine”.

public static string FormatCurrency(this decimal amount, string currencyCode)
	var 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)
		return amount.ToString("0.00");

	return string.Format(culture, "{0:C}", amount);

Here are the results of calling FormatCurrency for a few different currency codes:

decimal amount = 100;

amount.FormatCurrency("AUD");  //$100.00
amount.FormatCurrency("GBP");  //£100.00
amount.FormatCurrency("EUR");  //100,00 €
amount.FormatCurrency("VND");  //100,00 ₫
amount.FormatCurrency("IRN");  //₹ 100.00
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