Generate a unique id

Question

I am a student at university and our task is to create a search engine. I am having difficulty generating a unique id to assign to each url when added into the frontier. I have attempted using the SHA-256 hashing algorithm as well as Guid. Here is the code that i used to implement the guid:

public string generateID(string url_add) {     long i = 1;      foreach (byte b in Guid.NewGuid().ToByteArray())     {         i *= ((int)b + 1);     }      string number = String.Format("{0:d9}", (DateTime.Now.Ticks / 10) % 1000000000);      return number; } 

Answer 1

Why not just use ToString?

public string generateID() {     return Guid.NewGuid().ToString("N"); } 

If you would like it to be based on a URL, you could simply do the following:

public string generateID(string sourceUrl) {     return string.Format("{0}_{1:N}", sourceUrl, Guid.NewGuid()); } 

If you want to hide the URL, you could use some form of SHA1 on the sourceURL, but I'm not sure what that might achieve.

Answer 2

Why don't use GUID?

Guid guid = Guid.NewGuid(); string str = guid.ToString();