Unique 4 digit random number in C#

Question

I want to generate an unique 4 digit random number. This is the below code what I have tried:

Code for generating random number

//Ge         


        

Answer 1

Use this code instead:

private Random _random = new Random();

public string GenerateRandomNo()
{
    return _random.Next(0, 9999).ToString("D4");
}