How can I convert extended ascii to a System.String?

Question

For example: "½" or ASCII DEC 189. When I read the bytes from a text file the byte[] contains the valid value, in this case 189.

Converting to Unicode results in the Unicode replacement character 65533.

UnicodeEncoding.Unicode.GetString(b);

Converting to ASCII results in 63 or "?"

ASCIIEncoding.ASCII.GetString(b);

If this isn't possible what is the best way to handle this data? I'd like to be able to perform string functions like Replace().

Answer 1

It depends on exactly what the encoding is.

There's no such thing as "ASCII 189" - ASCII only goes up to 127. There are many encodings which a 8-bit encodings using ASCII for the first 128 values.

You may want Encoding.Default (which is the default encoding for your particular system), but it's hard to know for sure. Where did your data come from?

Answer 2

Byte 189 represents a "½" in iso-8859-1 (aka "Latin-1"), so the following is maybe what you want:

var e = Encoding.GetEncoding("iso-8859-1");
var s = e.GetString(new byte[] { 189 });

All strings and chars in .NET are UTF-16 encoded, so you need to use an encoder/decoder to convert anything else, sometimes this is defaulted (e.g. UTF-8 for FileStream instances) but good practice is to always specify.

You will need some form of implicit or (better) explicit metadata to supply you with the information about which encoding.