limiting the number of character in GUID

Question

is it possible or is there any overload to get a less than 32 characters of GUID ? currently i am using this statement but its giving me error

string guid = new Guid("{dddd-dddd-dddd-dddd}").ToString();

i want a key of 20 characters

If it had less characters, it wouldn't be a GUID. It would be some other not-so-random value. — Cody Gray - on strike, Jan 12 '12 at 14:42
Check out this answer to get it down to 20 characters using Ascii85 encoding: http://stackoverflow.com/a/3247983/945456 — Jeff B, Jan 04 '13 at 16:00
Do you want a GUID or do you want a 20 character value? They're not the same. — Peter Ritchie, Feb 21 '13 at 04:50

score 5 · Answer 1 · answered Jan 12 '12 at 14:40

You can use a ShortGuid. Here is an example of an implementation.

It's nice to use ShortGuids in URLs or other places visible to an end user.

The following code:

Guid guid = Guid.NewGuid();
ShortGuid sguid1 = guid; // implicitly cast the guid as a shortguid
Console.WriteLine( sguid1 );
Console.WriteLine( sguid1.Guid );

Will give you this output:

FEx1sZbSD0ugmgMAF_RGHw
b1754c14-d296-4b0f-a09a-030017f4461f

This is the code for an Encode and Decode method:

public static string Encode(Guid guid)
{
   string encoded = Convert.ToBase64String(guid.ToByteArray());
   encoded = encoded
     .Replace("/", "_")
     .Replace("+", "-");
   return encoded.Substring(0, 22);
}

public static Guid Decode(string value)
{
   value = value
     .Replace("_", "/")
     .Replace("-", "+");
   byte[] buffer = Convert.FromBase64String(value + "==");
   return new Guid(buffer);
}

This is 22 characters. The question states he wants 20 characters. You need to step up from BASE64 to ASCII85 to shave those 2 off. See David's answer. — Travis Watson, Dec 20 '13 at 19:47

score 2 · Answer 2 · answered Feb 21 '13 at 04:47

2

Use Jeff Attwood's ASCII85...

http://www.codinghorror.com/blog/2005/10/equipping-our-ascii-armor.html and http://www.codinghorror.com/blog/2005/10/c-implementation-of-ascii85.html

answered Feb 21 '13 at 04:47

David Gray Wright

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limiting the number of character in GUID

2 Answers2