How do I generate a random int number?

Question

How do I generate a random integer in C#?

Answer 1

I've tried all of these solutions excluding the COBOL answer... lol

None of these solutions were good enough. I needed randoms in a fast for int loop and I was getting tons of duplicate values even in very wide ranges. After settling for kind of random results far too long I decided to finally tackle this problem once and for all.

It's all about the seed.

I create a random integer by parsing out the non-digits from Guid, then I use that to instantiate my Random class.

public int GenerateRandom(int min, int max)
{
    var seed = Convert.ToInt32(Regex.Match(Guid.NewGuid().ToString(), @"\d+").Value);
    return new Random(seed).Next(min, max);
}

Update: Seeding isn't necessary if you instantiate the Random class once. So it'd be best to create a static class and call a method off that.

public static class IntUtil
{
   private static Random random;

   private static void Init()
   {
      if (random == null) random = new Random();
   }

   public static int Random(int min, int max)
   {
      Init();
      return random.Next(min, max);
   }
}

Then you can use the static class like so..

for(var i = 0; i < 1000; i++)
{
   int randomNumber = IntUtil.Random(1,100);
   Console.WriteLine(randomNumber); 
}

I admit I like this approach better.