1

I need to generate random int in C#. I am using clock time to set the seend. However, as the rnd.Next() function may take less than a millisecond, this does not work if one has to generate a list of ints.

        for( int i=0; i<5; i++) {
            int max_val = 10; // max value
            var rnd = new Random(DateTime.Now.Millisecond);
            int randind = rnd.Next(0, max_val);
            Console.WriteLine(randind);
        }

Output:
1 5 5 5 5

How can one randomise the seed in a clean way without adding an ugly sleep?

Nic
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2 Answers2

6

Create your Randomobject outside the loop and don't provide the seed parameter -- one will be picked for you. By taking it out of the loop, rnd.Next() will give you a random sequence anyway.

   var rnd = new Random();     
   for( int i=0; i<5; i++) {
        int max_val = 10; // max value
        int randind = rnd.Next(0, max_val);
        Console.WriteLine(randind);
    }
Steve Cooper
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2

The Guid Object guaranties a different result each time. You could do this:

... new Random(Guid.NewGuid().GetHashCode())

Milton Hernandez
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    The guid's expensive, and the hashcode's not guaranteed to be unique, so you're better off ignoring the seed constructor and just not constructing the Random instances over and over. – Steve Cooper Aug 23 '16 at 16:23