How to randomize seed in C# [duplicate]

Question

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?

Steve Cooper · Accepted Answer · 2016-08-23 16:03:45Z

8

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);
    }

answered Aug 23, 2016 at 16:03

Steve Cooper

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Bill Tür stands with Ukraine · Accepted Answer · 2022-08-26 08:05:42Z

5

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

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

edited Aug 26, 2022 at 8:05

Bill Tür stands with Ukraine

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answered Aug 23, 2016 at 16:04

Milton Hernandez

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1 Comment

Steve Cooper Over a year ago

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.

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