Generating random, unique values C#

Question

I've searched for a while and been struggling to find this, I'm trying to generate several random, unique numbers is C#. I'm using System.Random, and I'm using a DateTime.Now.Ticks seed:

public Random a = new Random(DateTime.Now.Ticks.GetHashCode()); private void NewNumber() {     MyNumber = a.Next(0, 10); } 

I'm calling NewNumber() regularly, but the problem is I often get repeated numbers. Some people suggested because I was declaring the random every time I did it, it would not produce a random number, so I put the declaration outside my function. Any suggestions or better ways than using System.Random ? Thank you

Answer 1

I'm calling NewNumber() regularly, but the problem is I often get repeated numbers.

Random.Next doesn't guarantee the number to be unique. Also your range is from 0 to 10 and chances are you will get duplicate values. May be you can setup a list of int and insert random numbers in the list after checking if it doesn't contain the duplicate. Something like:

public Random a = new Random(); // replace from new Random(DateTime.Now.Ticks.GetHashCode());                                 // Since similar code is done in default constructor internally public List<int> randomList = new List<int>(); int MyNumber = 0; private void NewNumber() {     MyNumber = a.Next(0, 10);     if (!randomList.Contains(MyNumber))         randomList.Add(MyNumber); }