C# Random Class

An example of generating a random number

In this example, five int (byte) numbers are generated randomly.

• First, a byte-type array is declared with four elements.
• Then, a random object is created and NextBytes method of the Random class is used to generate four random numbers.
• Finally, we used a foreach loop to display the random numbers as follows:

using System;

class Random_Example

{
    static void Main()
    {
        Random rand = new Random();

        byte[] randBytes = new byte[4];
        rand.NextBytes(randBytes);
        Console.WriteLine("Generated Numbers Are:");

        foreach (byte randVal in randBytes)
            Console.Write("{0, 4}", randVal);

        Console.ReadLine();
    }
}

The output as I executed this code:

The numbers should vary as you execute this code every time.

Using the Next method for generating int random numbers within a range

The following example shows using the Next method of the Random class and generating random numbers based on provided ranges.

For example, the first random number is generated between 1 – 100. The second is between 100 to 400 while the fourth is from 1000 to 10000.

The Code:

using System;

class Random_Num_Next

{
    static void Main()
    {
        Random rand = new Random();

        Console.WriteLine("The Generated Random Numbers Are: \n");
        Console.WriteLine(rand.Next(1, 100));
        Console.WriteLine(rand.Next(100, 500));
        Console.WriteLine(rand.Next(501, 1000));
        Console.WriteLine(rand.Next(1000, 10000));

        Console.ReadLine();
    }
}

The example of creating double-type random numbers

In the example below, we have an array of the double type with three elements.

The NextDouble method of the Random class is used as follows:

using System;

class Random_Example

{
    static void Main()
    {
        Random dbl_rand = new Random();

        double[] arr_rand_dbl = {
               dbl_rand.NextDouble(),
               dbl_rand.NextDouble() ,
               dbl_rand.NextDouble()
              };

        Console.WriteLine("Generated Double Random Numbers:\n");

        foreach (double rand_result in arr_rand_dbl)
        {
         Console.WriteLine(rand_result);
        }

        Console.ReadLine();
    }
}

You may also use:

That means you may also specify a number if you want to get the random number bigger or smaller.

An example of generating five random numbers within a range

The following example shows generating ten random numbers within the range of 1 and 1000. A for loop is used for that purpose as shown below:

using System;

class Random_Example_Ten
{
    static void Main()
    {
        Random range_rand = new Random();

        Console.WriteLine("Ten Random Numbers \n");

        for (int x = 1; x <= 10; x++)
            Console.Write(range_rand.Next(1, 1000) + "\n");
        Console.ReadLine();
    }
}

The output as this code is executed:

Generating ten random floating numbers

This example shows generating ten floating random numbers by using the NextDouble() method in the for loop. The random numbers are within the range of 1 and 4:

using System;

class Random_Example_Ten_Float
{
    static void Main()
    {
        Random range_rand_dbl = new Random();

        Console.WriteLine("Ten Random Floating Numbers \n");
        for (int z = 1; z <= 10; z++)
            Console.Write(range_rand_dbl.NextDouble() * 4 + "\n");

        Console.ReadLine();
    }
}