Random Class

[Cmonkey123]

Random Class

The System.Random class provided in .NET doesn't seem to be all that random...

I have a method that uses this class, it it always produces the same numbers:

		private void CalculatePop()
		{
			Random rand = new Random();

			//random percentages used to calc long values
			int randPopNotCiv = rand.Next( planetPopPer[0] - 1, planetPopPer[1] + 1 );
			int randPopNotCont = rand.Next( planetPopPer[2] - 1, planetPopPer[3] + 1 );
			int randPopPoor = rand.Next( planetPopPer[4] - 1, planetPopPer[5] + 1 );
			int randPopDiseasednc = rand.Next( planetPopPer[6] - 1, planetPopPer[7] + 1 );
			int randPopDiseasedp = rand.Next( planetPopPer[8] - 1, planetPopPer[9] + 1 );

			planetPopNotCiv = Math.Floor( ( planetPop * randPopNotCiv ) / 100 );
			planetPopNotCont = Math.Floor( ( planetPop * randPopNotCont ) / 100 );
			planetPopPoor = Math.Floor( ( planetPop * randPopPoor ) / 100 );
			planetPopDiseased = Math.Floor( ( ( planetPop * randPopDiseasednc ) / 100 ) + ( ( planetPop * randPopDiseasedp ) / 100 ) );
		}

The planetPopPer values aren't important, I don't have any problems with it... but it seems that no matter how I use this method it produces the same number 99% of the time, unless I completely restart the program.

Am I using the method improperly or is there another, possibly better, method that I could use to generate random numbers?

Any help would be greatly appreciated.

 

[arul]

The problem is that you create a new instance of the pseudo-random number generator every time you call the method, which is problem for time dependant random number generator.

This should fix your problem

        public static Random Rand;
	private void CalculatePop()
		{
			if ( Rand == null )
                              Rand = new Random();

			//random percentages used to calc long values
			int randPopNotCiv = Rand.Next( planetPopPer[0] - 1, planetPopPer[1] + 1 );
			int randPopNotCont = Rand.Next( planetPopPer[2] - 1, planetPopPer[3] + 1 );
			int randPopPoor = Rand.Next( planetPopPer[4] - 1, planetPopPer[5] + 1 );
			int randPopDiseasednc = Rand.Next( planetPopPer[6] - 1, planetPopPer[7] + 1 );
			int randPopDiseasedp = Rand.Next( planetPopPer[8] - 1, planetPopPer[9] + 1 );

			planetPopNotCiv = Math.Floor( ( planetPop * randPopNotCiv ) / 100 );
			planetPopNotCont = Math.Floor( ( planetPop * randPopNotCont ) / 100 );
			planetPopPoor = Math.Floor( ( planetPop * randPopPoor ) / 100 );
			planetPopDiseased = Math.Floor( ( ( planetPop * randPopDiseasednc ) / 100 ) + ( ( planetPop * randPopDiseasedp ) / 100 ) );
		}

 

[Cmonkey123]

Ah I see! Thanks very much!

 

[Cmonkey123]

Actually, one more question...

What if I am calling a bunch of random operations in the same method? For example I have a method that randomizes an array of 46 integers and then adds them together to get a large double number:

		private void NewPop()
		{
			if( randNPop == null )
				randNPop = new Random();

			int[] randomPopInt = new int[46];

			int intCount = 0;
			foreach( int i in randomPopInt )
			{
				if( isNotMoon == true )
					randomPopInt[intCount] = randNPop.Next( 21739, 75000000 );
				else
					randomPopInt[intCount] = randNPop.Next( 22, 21739130 );

				planetPop = planetPop + Convert.ToDouble( randomPopInt[intCount].ToString() );

				randomPopInt[intCount] = 0;

				intCount++;
			}
		}

I can't use the NextDouble method either because I need the random number to be between certain values. How would I use the Random class so that their values are more random?

 

[arul]

Use RandomNumberGenerator class to get "more" random numbers ( from System.Security.Cryptography namespace ).

 

[RunUO2874]

Or Utility.Random

 

[arul]

Or Utility.Random

Utility random uses System.Random to generate random numbers.
Besides that, Cmonkey123 probably wants it for external application.

 

[daat99]

Utility random uses System.Random to generate random numbers.
Besides that, Cmonkey123 probably wants it for external application.

He can duplicate the utility.random to fit his needs relatively easy

 

[Cmonkey123]

Yea it's an external app, but maybe I will take a look at the utility.random script, thanks!