[RESOLVED] C# Random Methods

[Krunchyman]

I've been trying to write a C# program that generates random sentences. I've succeeded but I have one problem. For example, the random methods seem to only generate the same 1 random number even though I have 3. Thus, only about 9 sentences can actually be generated. After doing some testing, it appears that some sentences tend to be unique because the random methods generate numbers from a range of (1, 8) up to (1, 10).

How do I make it so the random integers are private, rather than displayed/calculated as 1 integer?

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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            /* The program will close if the letter "Q" is entered at the first 'Console.ReadLine'.
             * The loops are messy but I will fix that after I get the random number methods working.
             */
            string x;
            Console.WriteLine("Press any key to start:");
            x = Console.ReadLine();

            do
            {
                //These 3 random methods only generate 1 number.
                int n;
                Random rand1 = new Random();
                n = rand1.Next(0, 8);
                string[] names = { "Bo ", "Rad ", "Jimbo ", "Bill ", "Waldo ", "Vladislav ", "Tommy ", "Moses " };

                int v;
                Random rand2 = new Random();
                v = rand2.Next(0, 9);
                string[] verbs = { "killed ", "ate ", "touched ", "saw ", "talked to ", "brazed ", "threw a stone at ", "challenged ", "tickled " };

                int o;
                Random rand3 = new Random();
                o = rand3.Next(0, 10);
                string[] objects = { "a box ", "a wall ", "a stone ", "a machine ", "a pill ", "a fruit", "a zombie ", "a cat ", "a cornflake ", "a mugger " };

                string r;
                /*The n/o/v integers should be different but they are all the same. 'String[] names' has 9
                 * words so only about 9 types of sentences are generated, rather than the potential 720 sentences.
                */
                Console.WriteLine(names[n] + verbs[v] + objects[o]);
                r = Console.ReadLine();
            }
            while (x != "Q");
        }
    }
}

The code acts very unpredictable so I believe it is best for anyone who wishes to figure out the problem compile and run it to observe how it works. I am using Visual C# Express 2010.

[BioPhysEngr]

I think what's happening is that each call to new Random() initializes a pseudo-random number generator seeded based on the time the call occurred. Since these all happen almost simultaneously, they all get initialized with the same value and thus produce a coordinated answer.

Usually, I declare one random number generator at the start (or even for the whole class) and call it. That is do:

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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            /* The program will close if the letter "Q" is entered at the first 'Console.ReadLine'.
             * The loops are messy but I will fix that after I get the random number methods working.
             */
            string x;
            Console.WriteLine("Press any key to start:");
            x = Console.ReadLine();
            
            Random rng = new Random(); //Declare once

            do
            {
                //These 3 random methods only generate 1 number.
                int n;
                n = rng.Next(0, 8);
                string[] names = { "Bo ", "Rad ", "Jimbo ", "Bill ", "Waldo ", "Vladislav ", "Tommy ", "Moses " };

                int v;
                v = rng.Next(0, 9);
                string[] verbs = { "killed ", "ate ", "touched ", "saw ", "talked to ", "brazed ", "threw a stone at ", "challenged ", "tickled " };

                int o;
                o = rng.Next(0, 10);
                string[] objects = { "a box ", "a wall ", "a stone ", "a machine ", "a pill ", "a fruit", "a zombie ", "a cat ", "a cornflake ", "a mugger " };

                string r;
                /*The n/o/v integers should be different but they are all the same. 'String[] names' has 9
                 * words so only about 9 types of sentences are generated, rather than the potential 720 sentences.
                */
                Console.WriteLine(names[n] + verbs[v] + objects[o]);
                r = Console.ReadLine();
            }
            while (x != "Q");
        }
    }
}

[Krunchyman]

Thanks. Is there any way I can delay the call for a certain amount of milliseconds to get better randomness? The change would be unnecessary but I am curious to know how it could be done.

[BioPhysEngr]

Thread.Sleep ought to work. See: http://msdn.microsoft.com/en-us/library/d00bd51t.aspx

You can also pass your own seed to the Random class like: new Random(seed).

If you need cryptographic-strength randomness (you don't for this application), you can also use the RNGCryptoServiceProvider class; see http://japikse.blogspot.com/2008/10/...bers-in-c.html

[Krunchyman]

Ok, thanks.