Math Random Coin Toss

Question

I wrote a function A, and inside this function there is below code piece.

rnd.Next(1,3);

If I run my A function hundred times, and print out the results, results are not realistic for example it is always win or always lose. So the random function is problematic. I need a realistic real random function.

How to achieve that ?

Could you show us the rest of the code (where you run `A` a hundred times and collect results)? — Douglas, Jan 10 '14 at 09:32
Let me guess, you're seeding `rnd` inside the function, every time? — Oliver Charlesworth, Jan 10 '14 at 09:32
[Have a read of this](http://stackoverflow.com/a/768001/838807) — musefan, Jan 10 '14 at 09:33

Dmitry Bychenko · Accepted Answer · 2014-01-10T10:20:49.903

I guess you've done a typical error with Random, you're re-creating it each time i.e:

  Random rnd = new Random();
  int toss = rnd.Next(1,3);

If you do this, rnd could well start each time from the same seed and that's why the result is badly skewed. The solution can be something like that:

   // Let it be thread-safe
   private static ThreadLocal<Random> s_Gen = new ThreadLocal<Random>(
    () => new Random());

   // Thread-safe non-skewed generator
   public static Random Generator {
     get {
       return s_Gen.Value;
     }
   }

   ...

   int toss = Generator.Next(1,3);

score 1 · Answer 2 · edited May 23 '17 at 10:25

1

Use this

int i = rnd.Next(int.MaxValue) % 2;

Then have a check whether i = 0 or i = 1.

EDIT Yes, as Dmitry Bychenko mentioned do not instantiate a new Random object each time.

edited May 23 '17 at 10:25

Community

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answered Jan 10 '14 at 09:45

Deepak Bhatia

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Math Random Coin Toss

2 Answers2