YouTube-like GUID

Question

Is it possible to generate short GUID like in YouTube (N7Et6c9nL9w)?

How can it be done? I want to use it in web app.

Answer 1

It's not a GUID

Let me jump in with the following

It uses the TotalMilliseconds from EPOCH and a valid set of characters.

This will not be globally unique but unique to the instance where it's defines

public string YoutubeLikeId()
{
    Thread.Sleep(1);//make everything unique while looping
    long ticks = (long)(DateTime.UtcNow.Subtract(new DateTime(1970, 1, 1,0,0,0,0))).TotalMilliseconds;//EPOCH
    char[] baseChars = new char[] { '0','1','2','3','4','5','6','7','8','9',
            'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z',
            'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x'};

    int i = 32;
    char[] buffer = new char[i];
    int targetBase= baseChars.Length;

    do
    {
        buffer[--i] = baseChars[ticks % targetBase];
        ticks = ticks / targetBase;
    }
    while (ticks > 0);

    char[] result = new char[32 - i];
    Array.Copy(buffer, i, result, 0, 32 - i);

    return new string(result);
}

The output will come something like

XOTgBsu
XOTgBtB
XOTgBtR
XOTgBtg
XOTgBtw
XOTgBuE

Update: The same can be achieved from Guid as

var guid = Guid.NewGuid(); 
guid.ToString("N");
guid.ToString("N").Substring(0,8);
guid.ToString("N").Substring(8,4);
guid.ToString("N").Substring(12,4);
guid.ToString("N").Substring(16,4);
guid.ToString("N").Substring(20,12);

For a Guid ecd65132-ab5a-4587-87b8-b875e2fe0f35 it will break it down in chunks as ecd65132 ,ab5a , 4587,87b8,b875e2fe0f35

but i can't guarantee it to be unique always.

Update 2: There is also a project called ShortGuid to get a url friendly GUID it can be converted fron/to a regular Guid