C# – How to convert a Unicode character to its ASCII equivalent


Here's the problem:

In C# I'm getting information from a legacy ACCESS database. .NET converts the content of the database (in the case of this problem a string) to Unicode before handing the content to me.

How do I convert this Unicode string back to it's ASCII equivalent?

Unicode char 710 is indeed MODIFIER LETTER CIRCUMFLEX ACCENT. Here's the problem a bit more precise:

 -> (Extended) ASCII character ê (Extended ASCII 136) was inserted in the database.
 -> Either Access or the reading component in .NET converted this to U+02C6 U+0065
 -> I need the (Extended) ASCII character 136 back.

Here's what I've tried (I see now why this did not work…):

string myInput = Convert.ToString(Convert.ToChar(710));
byte[] asBytes = Encoding.ASCII.GetBytes(myInput);

But this does not result in 94 but a byte with value 63…
Here's a new try but it still does not work:

byte[] bytes = Encoding.ASCII.GetBytes("ê");

Thanks to both csgero and bzlm for pointing in the right direction I solved the problem here.

Best Answer

Okay, let's elaborate. Both csgero and bzlm pointed in the right direction.

Because of blzm's reply I looked up the Windows-1252 page on wiki and found that it's called a codepage. The wikipedia article for Code page which stated the following:

No formal standard existed for these ‘extended character sets’; IBM merely referred to the variants as code pages, as it had always done for variants of EBCDIC encodings.

This led me to codepage 437:

n ASCII-compatible code pages, the lower 128 characters maintained their standard US-ASCII values, and different pages (or sets of characters) could be made available in the upper 128 characters. DOS computers built for the North American market, for example, used code page 437, which included accented characters needed for French, German, and a few other European languages, as well as some graphical line-drawing characters.

So, codepage 437 was the codepage I was calling 'extended ASCII', it had the ê as character 136 so I looked up some other chars as well and they seem right.

csgero came with the Encoding.GetEncoding() hint, I used it to create the following statement which solves my problem:

byte[] bytes = Encoding.GetEncoding(437).GetBytes("ê");