Generic string encoder in C#

Question

What I need is very simple, but before I reinvent the wheel, I would like to know if something similar exist in the framework already.

I would like to encode (and decode) strings from a predefined characters table. I have many strings that contains few characters. Here is a string I would like to encode:

cn=1;pl=23;vf=3;vv=0

This string size is 20 chars, so 20 bytes.

In the string, I only use the following characters: cn=1;p23vf0

A total of 11 characters. So each character can be encoded with 4 bits only isn't ? Reducing the total amount of bytes used to 10.

Is there any existing method in .NET that can take a string in parameter and the reference table array and return the encoded bytes ?

char[] reference = "cn=1;p23vf0".ToCharArray(); string input = "cn=1;pl=23;vf=3;vv=0";

byte[] encoded = someClass.Encode(input, reference); string decoded = someClass.Decode(encoded, reference);

Assert.AreEqual(input, decoded);

Answer 1

Any compression algorithm uses Huffman encoding. Which is basically what you are looking for here. That encoding isn't exposed as a class separately, it is part of the algorithm of the DeflateStream and GZipStream classes. Which is what you ought to use, as long as your strings are a reasonable size. If they are short then there isn't any point in encoding them.