.NET Short Unique Identifier

Question

I need a unique identifier in .NET (cannot use GUID as it is too long for this case).

Do people think that the algorithm used here is a good candidate or do you have any other suggestions?

Answer 1

This one a good one - http://www.singular.co.nz/blog/archive/2007/12/20/shortguid-a-shorter-and-url-friendly-guid-in-c-sharp.aspx

and also here YouTube-like GUID

You could use Base64:

string base64Guid = Convert.ToBase64String(Guid.NewGuid().ToByteArray());

That generates a string like E1HKfn68Pkms5zsZsvKONw==. Since a GUID is always 128 bits, you can omit the == that you know will always be present at the end and that will give you a 22 character string. This isn't as short as YouTube though.

Answer 2

I use a similar approach as Dor Cohen's but removing some special characters:

var uid = Regex.Replace(Convert.ToBase64String(Guid.NewGuid().ToByteArray()), "[/+=]", "");     

This will output just alphanumeric characters. The UIDs are not guaranteed to have always the same length. Here is a sample run:

vmKo0zws8k28fR4V4Hgmw 
TKbhS0G2V0KqtpHOU8e6Ug 
rfDi1RdO0aQHTosh9dVvw
3jhCD75fUWjQek8XRmMg 
CQUg1lXIXkWG8KDFy7z6Ow 
bvyxW5aj10OmKA5KMhppw
pIMK8eq5kyvLK67xtsIDg
VX4oljGWpkSQGR2OvGoOQ 
NOHBjUUHv06yIc7EvotRg
iMniAuUG9kiGLwBtBQByfg

Answer 3

var ticks = new DateTime(2016,1,1).Ticks;
var ans = DateTime.Now.Ticks - ticks;
var uniqueId = ans.ToString("x");

Keep a baseline date (which in this case is 1st Jan 2016) from when you will start generating these ids. This will make your ids smaller.

Generated Number: 3af3c14996e54