How would you create a unique random number that isn't in a list?

Question

I'm trying to create a method that stores a unique random number to a class, and the way I am checking if it is unique is by looking through a list that contains an int, string and date. I'm just sort of stuck on how you would have it just search the ints of the list.

Possible duplicate: http://stackoverflow.com/questions/1011198/non-repetitive-random-number-c-sharp or http://stackoverflow.com/questions/5561742/generate-distinct-random-numbers-in-c-sharp — Sam, Nov 16 '13 at 17:44
possible duplicate of [How to generate "random" but also "unique" numbers?](http://stackoverflow.com/questions/909983/how-to-generate-random-but-also-unique-numbers) — Kurubaran, Nov 16 '13 at 17:44
no those can still create a number that is in the list, even if they are unique — , Nov 16 '13 at 18:01

Juan · Answer 1 · 2013-11-16T20:52:24.763

0

You can use a guid, is based in your computer id and date. Is by definition a unique string every time.

use Guid.NewGuid()

Well if it is just numbers you can use a mathematical function like this one here then use the current date to limit our possible numbers and use the random functions to generate your unique number.

You can use in c# this DateTime.Ticks to get there.

edited Nov 16 '13 at 20:52

answered Nov 16 '13 at 20:15

Juan

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A `Guid` is not an `int` though. – Nov 16 '13 at 20:30

score 0 · Answer 2 · answered Nov 16 '13 at 21:14

Use Math.Random Class. See here i m using this class to generate password. You can specify what are the data it should support. if you need integer only then you can specify (1 to 9 and 0). Here is one example.

    private string CreatePassword(int length)
    {
        string valid = "1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz@#$";
        string res = "";
        Random rnd = new Random();
        while (0 < length--)
            res += valid[rnd.Next(valid.Length)];
        return res;
    }

    public void InitializeData()
    {
        string password = CreatePassword(6);
    }

How would you create a unique random number that isn't in a list?

2 Answers2