Question

i am trying to generate random number for my mental math quiz game. But i think i am doing something wrong.Please help me to correct my code.Please try to include some sort of explanation, why my code is incorrect. Thanks in advance!

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


    namespace MindTraining
    {
        class Program
        {
            static void Main(string[] args)
            {

                Console.WriteLine("Enter the digits of first number ");
                int a=int.Parse(Console.ReadLine());
                Console.WriteLine("Enter the digits of second number");
                int b = int.Parse(Console.ReadLine());

                Random RandomClass = new Random(DateTime.UtcNow.Second);

                int RandomNumber = RandomClass.Next(10^(a-1), 10^a);
                Console.WriteLine(RandomNumber);
    }


    }

}

What i am trying to achieve is , I want user to enter number of digits in number a and number of digits in number b

Then program would generate random number, say user entered 2 for a ,then program have to generate numbers between 0 to 10(Random Number, Every time different)

if user entered 3 for a, then between 10 to 100,

Similar thing for b, and then calculating product.Number should not repeat more than 2 times, during program run time.

Ok, i changed my code to

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


namespace MindTraining
{
    class Program
    {
        static void Main(string[] args)
        {

            Console.WriteLine("Enter the digits of first number ");
            int a=int.Parse(Console.ReadLine());
            Console.WriteLine("Enter the digits of second number");
            int b = int.Parse(Console.ReadLine());

            Random RandomClass = new Random(DateTime.UtcNow.Second);
            double num1=Math.Pow(10,a-1);
            double num2=Math.Pow(a,1);
            int num3 = Convert.ToInt32( num1);
            int num4=Convert.ToInt32(num2);

            int RandomNumber = RandomClass.Next(num3,num4);
            Console.WriteLine(RandomNumber);
}}

// But still not getting result, I throws error,

This one worked!

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


namespace MindTraining
{
    class Program
    {
        static void Main(string[] args)
        {

            Console.WriteLine("Enter the digits of first number ");
            int a=int.Parse(Console.ReadLine());
            Console.WriteLine("Enter the digits of second number");
            int b = int.Parse(Console.ReadLine());

            Random RandomClass = new Random();
            double num1=Math.Pow(10,(a-1));
            double num2=Math.Pow(10,(a));
            int num3 = Convert.ToInt32( num1);
            int num4=Convert.ToInt32(num2);

            int RandomNumber = RandomClass.Next(num3,num4);
            Console.WriteLine(RandomNumber);
}


}






        }

Answer 1

is there any reason you want to use a seed value that is so limited? Why not use

Random RandomClass = new Random();

which takes a default time based seed value for your object?

Also, use Math.pow(base,exp) to calculate the range for your Random.next() calls as:

int RandomNumber = RandomClass.Next((int)Math.Pow(10,(a-1)), (int)Math.Pow(10,a));

In your code, the error occurs because,

double num2=Math.Pow(a,1);

returns a itself. So, your maxvalue in the Random.next() is lower than your minvalue, which is logically incorrect. This is the error, I got from running your code, that is apart from the fact that you are missing a closing brace at the end.

Also, you must realise that there is no such thing as a perfectly random number generator. All these are pseudo-random generators. They follow the normal distribution of numbers on the number line. So, to say that a number will not be generated more than twice in one execution is not feasible unless you store all the numbers generated and keep checking against them. This should be a last resort, only is case of dire requirements.