Converting country codes in .NET

Question

In .NET is there any way to convert from three letter country codes (defined in ISO 3166-1 alpha-3) to two letter language codes (defined in ISO 3166-1 alpha-2) eg. convert

Answer 1

Some of the above answers are O(N) for lookups, which is fine if you're only doing it once, but generally you'll want to call this more than once per process in which case you'll probably want something more efficient.

var Iso3ToIso2Mapping = CultureInfo.GetCultures(CultureTypes.SpecificCultures)
  .Select(ci => new RegionInfo(ci.LCID))
  .GroupBy(ri => ri.ThreeLetterISORegionName)
  .ToDictionary(g => g.Key, g => g.First().TwoLetterISORegionName);

Then you can just do a lookup with:

var iso2CountryCode = Iso3ToIso2Mapping["AUS"];
Console.WriteLine(iso2CountryCode);

Prints:

AU