# Storing a DNS name as compactly as possible in memory (preferably in C#) [closed]

What is the most compact way to encode/save DNS names in memory?

For example, storing "www.google.com" as a string in .NET will result in the object being encoded as UTF-16, and it will consume twice as much memory as plain ASCII... but for the purpose of storing DNS names, ASCII is overkill.

The only characters that are needed are:

• A..Z (case insensitive)
• 0..9
• Hyphen
• underscore
• period
• Asterisk (not legal DNS, but used in ACLs such as *.google.com) always as a leading character, never elsewhere.

A total of 40 characters.. which fits within single byte with plenty room to spare.

My code golf question/challenge is what is the most compact way to store a string of characters in memory and maximizing in memory storage?

The inspiration for this challenge came from this blog entry.

• How do you win the competition? – beary605 Oct 21 '12 at 6:44
• You meant UTF-16 for the .NET framework. In UTF-8, this name would take up just as much as ASCII. – Mr Lister Oct 21 '12 at 7:00
• Try cs.stackexchange.com - there's probably already a question about basic information theory which would tell you all you need to know. – Peter Taylor Oct 21 '12 at 8:01
• – beary605 Oct 21 '12 at 15:48
• As stated this looks like a question for Stack Overflow (that is, it is a question). CodeGolf.SE is a plce for playing certain programming games. It would be essentially trivial to turn this into a [code-golf]---you just add the tag (and probably the one @beary suggests as well) and resign yourself to getting answer many languages. But I am closing until that is done just to encourage you to read the FAQ before posting to a new Stack Exchange site. Flag when you are ready for this to be re-opened. – dmckee --- ex-moderator kitten Oct 21 '12 at 19:10

You could interpret it as a base 39 number. Since only the first character can be an asterisk, you can encode it as the sign. If i use the characters as digits in the order you named them, www.google.com would be 10903065870001232914011 in decimal and 24f0e6f41d8ecd3a65b in hex, which could be stored in 10 bytes.
*.google.com would be -310664672884413873 in decimal and fbb04c2040762a4f in hex, if you store it in 8 bytes.
• gzip on a file containing www.google.com gives 42 bytes. – ugoren Oct 21 '12 at 11:11