c# returning array from function gives same result when recalled

Question

Got an issue where my code will generate numbers for the user and then generate numbers to compare against, although when I call this multiple times it always comes out with the same numbers even though it is supposed to be random for each call.

An example of my output is:

17,41,47,46,21,39,18

And when I call the function again I get the same output as above even though I call the function again which should produce new numbers

Menu options:

case 1:
    ticketNumbers = PlayerPickNumbers();
    CheckWinningTicket(ticketNumbers);
    break;
case 2:
    ticketNumbers = AIPickNumbers();
    CheckWinningTicket(ticketNumbers);
    break;

Random number method....

static int[] AIPickNumbers() 
    {
        int[] numbersPicked = new int[7]; // Digit 7 is bonus ball
        int randomPicked = 0;
        Random rnd;
        rnd = new Random();

        for (int i = 0; i < 7; i++)
        {

            randomPicked = rnd.Next(1, 50);

            while (numbersPicked.Contains(randomPicked) == false)
            {
                numbersPicked[i] = randomPicked;
            }

            Console.Write(randomPicked + ",");
        }
        Console.WriteLine();

        return numbersPicked;
    }

Winning Ticket method...

static void CheckWinningTicket(int[] userNumbers)
    {
        int[] winningNumbers = new int[7];
        winningNumbers = AIPickNumbers(); // Generate winning numbers to compare against
        int[] userPickedNumbers = new int[7];
        userPickedNumbers = userNumbers;

        int totalmatches = 0;

        totalmatches = winningNumbers.Intersect(userPickedNumbers).Count();

        Console.WriteLine("You had " + totalmatches + " match(es)");


    }

I think the issue is when random is createdit is being created too fast and as such will always return the same numbers but not 100% sure.

[`Random`](https://msdn.microsoft.com/en-us/library/system.random(v=vs.110).aspx) is a PRNG (pseudorandom number generator), not a source of 'true' randomness. It's deterministic: the same internal state always produces the same 'random' number. That internal state is initialized with a seed value. If you don't specify a seed yourself, a time-dependent value is used - so if you create multiple `Random` instances in quick succession it's very likely that they will have the same internal state - and thus produce the same numbers. — Pieter Witvoet, Mar 10 '17 at 09:36
So in short I need to do something such as: Random rnd = new Random(Guid.NewGuid().GetHashCode()); — Robertgold, Mar 10 '17 at 09:39

c# returning array from function gives same result when recalled

0 Answers0