How Do I Roll Dice in C#?

Simulating 10 million Dice Rolls

This application uses one instance of the Random() class in the object rnd. It also allocates enough space to hold the totals for scores 3..18 in the array Rolls[]. Member functions OneDice() returns a value between 1 and 6 - rnd.Next(n) returns values in the range 0..n-1, while ThreeDice() calls OneDice() three times. The constructor for the RollDice() clears the Rolls array then calls ThreeDice() however many times (10 million in this case) and increments the appropriate Rolls[] element.

The last part is to print out the generated totals to see that it generates throws in accordance with the probabilities. A 6 sided dice has an average score of 3.5, so three dice should average about 10.5. The totals for 10 and 11 are roughly the same and occur about 12.5% of the time.

Here is the output of a typical run. It takes no more than a second. Because it's a console application, I included a

Console.ReadKey();

To wait until you hit a key before closing.

Program Output

3 46665
4 138772
5 277440
6 463142
7 693788
8 971653
9 1157160
10 1249360
11 1249908
12 1159074
13 972273
14 695286
15 463270
16 277137
17 138633
18 46439

Program Listing

using System;
using System.Collections.Generic;
using System.Text;


namespace exrand
{
    public class RollDice
    {
        private Random rnd= new Random() ;
        private int[] Rolls = new int[19]; // Holds 3 to 18

        public int OneDice() {
            return rnd.Next(6)+1;
        }

        public int ThreeDice()
        {
            return OneDice() + OneDice() + OneDice() ;
        }

        public RollDice(int Count)
        {
            int i = 0;
            for (i=3;i<=18;i++)
                Rolls[ i ] =0;
            for (i = 0; i < Count; i++)
            {
                int total = ThreeDice() ;
                Rolls[total]++;
            }
            for (i = 3; i <= 18; i++)
            {
                Console.WriteLine("{0} {1}",i,Rolls[ i ]) ;
            }
            Console.ReadKey() ;
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            RollDice Rand = new RollDice(10000000) ;
        }
    }
}