Question Decode cyrillic string (RFC 1522)

[daniel.dfg]

Hi all,

I hope you can help me how I can resolve this using VB.NET

From a third-party tool I receive a string which is originally in cyrillic (koi8-r)

The string is always written in this format:

"=?" charset "?" encoding "?" encoded-text "?="

This standard comes from the definition of RFC 1522
http://www.ietf.org/rfc/rfc1522.txt


One string I have to decode can look like this:

=?koi8-r?Q?56552813_=CE=C5_=C4=CC=D1_DPC?=

The encoding "Q" mixes readable text with encoded characters like "CE".
How can I retreive the correctly decoded string by use of VB.NET?

Thank you so much in advance,
Daniel

 

[JohnH]

I recommend Regex to find the encoded-word pattern and extract the charset part and the text part, and the Q/B part if you need it. With charset you can get an Encoding object. Then I would use Regex again to replace all '=XX' entities with the relevant characters. As for the hexadecimal values, like "CE", you must parse that string into a Byte value using Byte.Parse method and use that value as input for the encodings GetString method.

 

[daniel.dfg]

Hi John,

Thank you, this sounds good. The Extraction of the Byte Values is fine for me. But could you show me how you would solve the parsing in vb.net code?

 

[JohnH]

Instead of me posting code you wouldn't understand and not learn anything from I suggest you start by learning regular expressions and give it a go yourself. Try this place: Regular-Expressions.info - Regex Tutorial, Examples and Reference - Regexp Patterns
How would you write the regex to match the =?charset?Q?encodedtext?= pattern?