HTML Encode ISO-8859-2 (Latin-2) characters in C#

Question

Anyone knows how to encode ISO-8859-2 charset in C#? The following example does not work:

        String name = "Filipović";
        String encoded = WebUtility.HtmlEncode(name);

The resulting string should be

"Filipović"

Thanks

Answer 1

After reading your comments (you should support also Chinese names using ASCII chars only) I think you shouldn't stick to ISO-8859-2 encoding.

Solution 1

Use UTF-7 encoding for such names. UTF-7 is designed to use only ASCII characters for any Unicode string.

string value = "Filipović with Unicode symbol: ";
var encoded = Encoding.ASCII.GetString(Encoding.UTF7.GetBytes(value));
Console.WriteLine(encoded); // Filipovi+AQc- with Unicode symbol: +2Dzf7w-
var decoded = Encoding.UTF7.GetString(Encoding.ASCII.GetBytes(encoded));

Solution 2

Alternatively, you can use base64 encoding, too. But in this case the pure ASCII strings will not be human-readable anymore.

string value = "Filipović with Unicode symbol: ";
encoded = Convert.ToBase64String(Encoding.UTF8.GetBytes(value));
Console.WriteLine(encoded); // RmlsaXBvdmnEhyB3aXRoIFVuaWNvZGUgc3ltYm9sOiDwn4+v
var decoded = Encoding.UTF8.GetString(Convert.FromBase64String(encoded));

Solution 3

If you really stick to HTML Entity encoding you can achieve it like this:

string value = "Filipović with Unicode symbol: ";

var result = new StringBuilder();       
for (int i = 0; i < value.Length; i++)
{
    if (Char.IsHighSurrogate(value[i]))
    {
        result.Append($"&#{Char.ConvertToUtf32(value[i], value[i + 1])};");
        i++;
    }
    else if (value[i] > 127)
        result.Append($"&#{(int)value[i]};");
    else
        result.Append(value[i]);
}

Console.WriteLine(result); // Filipovi&#263; with Unicode symbol: &#127983;

Answer 2

If you don't have strict requirement on Html encoding I'd recommend using Url (%) encoding which encodes all non-ASCII characters:

String name = "Filipović";
String encoded = WebUtility.UrlEncode(name); // Filipovi%C4%87

If you must have string with all non-ASCII characters to be HTML encoded consistently your best bet is use &xNNNN; or &#NNNN; format to encode all characters above 127. Unfortunately there is no way to convience HtmlEncode to encode all characters, so you need to do it yourself i.e. similarly how it is done in Convert a Unicode string to an escaped ASCII string. You can continue using HtmlDecode to read the values back at it handles &#xNNNN just fine.

Non optimal sample:

  var name = "Filipović";
  var result = String.Join("", 
     name.Select(x => x < 127 ? x.ToString() : String.Format("&#x{0:X4}", (int)x))
  );