C# Discussion Boards - CodeProject

19-Feb-09 4:00

does anybody know how to create guid like 3Ie7Y3GHayk on youtube ? can you show the code to create?

Calin Tatar19-Feb-09 4:06

19-Feb-09 4:06

.NET provides you the Guid class.

Guid.NewGuid().ToString()

returns in this format:

96699264-91F8-4afd-AC26-CCF243B279DC

Calin

Member 400536019-Feb-09 4:14

19-Feb-09 4:14

it's very agly string. how can i make it like in youtube.com guids

Calin Tatar19-Feb-09 4:20

19-Feb-09 4:20

you may use only a part from it, or remove the dashes.
Also you may use different formatters:

.ToString("N")
.ToString("D")
.ToString("B")
.ToString("P")

Do you want to be nice and simple to guess (the algorithm), or really random and good for security?

Calin

Member 400536019-Feb-09 4:23

19-Feb-09 4:23

i need to use it in url so i need it more nicely

Calin Tatar19-Feb-09 4:27

19-Feb-09 4:27

Anyway I think its very nice structured and really looks like a strong cipher.

Look...Microsoft is using it on downloads page: http://www.microsoft.com/downloads/details.aspx?FamilyID=941b3470-3ae9-4aee-8f43-c6bb74cd1466&DisplayLang=en[^]

Calin

Member 400536019-Feb-09 4:30

19-Feb-09 4:30

and look in youtube http://www.youtube.com/watch?v=1GCqDiLX1dI. so the question was how to make like in youtube

Calin Tatar19-Feb-09 4:35

19-Feb-09 4:35

you may use a few chars from a guid.

Calin

Thomas Stockwell19-Feb-09 5:26

Thomas Stockwell

19-Feb-09 5:26

Just create a loop that creates random characters from 0-9 and a-z and A-Z. Then combine them for the specified length.

Calin Tatar19-Feb-09 4:34

http://en.wikipedia.org/wiki/Globally_Unique_Identifier[^]

19-Feb-09 4:34

Ennis Ray Lynch, Jr.19-Feb-09 4:12

Ennis Ray Lynch, Jr.

19-Feb-09 4:12

I would imagine that 3Ie7Y3GHayk may resolve into something less than random.

Could just be base 26 or 52 integers.

457895210125864₁₀=368I5E292I4₂₆

Mirko198019-Feb-09 4:39

Mirko1980

19-Feb-09 4:39

Having also numbers, I guess it's a base-62 number.
Making some calculation, 11 base-62 digits are roughly equivalent to 64 base-2 digits.

So I guess that a code like 3Ie7Y3GHayk is a base-62 encoded Int64 value.

A guid is 128 bits, so, if you want to generate this code starting from a Guid you must use half of it. I'm not sure that doing so introduces the risk of conflicting ids.

If you want something quick&dirty, you could try the following code (I used base64 that is directly provided by the framework, but keep in mind that the resulting string can containg characters like '/' or '+' that might cause problems when put in urls). Otherwise you must write your own encoding algorithm.

Guid guid = Guid.NewGuid(); // original GUID
byte[] guidArray = guid.ToByteArray(); // byte array containing GUID data
byte[] halfArray = new byte[8]; // byte array that will contain half GUID data
Array.Copy(guidArray, halfArray, halfArray.Length); // getting half GUID (first half, maybe the second half is better???)
string id = Convert.ToBase64String(halfArray).Substring(0, 11); // convering into base64 and removing the trailing '='

Ennis Ray Lynch, Jr.19-Feb-09 4:42

Ennis Ray Lynch, Jr.

19-Feb-09 4:42

The problem with the grid is scalability from the randomness. That is why I suggested they probably aren't using a random number.