How to generate random numbers in C#

Overview

The C# language provides a built-in class, Random, for generating random numbers based on a seed value. By default, the Random class uses a system clock to generate a seed value.

The Random class provides the following methods to generate random numbers.

1. The Next() method

This method generates a random positive number within the range -2,147,483,648 to 2,147,483,647.

Syntax

Random random = new Random();

int num = random.Next();
Syntax of the Next() method

Example

Let's see an example of the Next() method in the code snippet below:

using System;



class Example

{

    static void Main()

    {

        // instantiate Random class

        Random random = new Random();



        // generate a random number

        int n = random.Next();



        // print the number of console

        Console.WriteLine("Random number: {0}", n);

    }

}

Explanation

Inside the main() function:

  • Line 8: We instantiate the Random class and create an object called random.
  • Line 11: We generate a random positive number using the Next() method.
  • Line 14: We print the random number on the console.

2. The Next(int) method

This method generates a random number that is less than the specified integer. Here, the specified integer acts as the upper bound.

Syntax

Random random = new Random();

int num = random.Next(int);
Syntax of the Next(int) method

Example

Let's see an example of the Next(int) method in the code snippet below:

using System;



class Example

{

    static void Main()

    {

        // instantiate Random class

        Random random = new Random();



        // generate a random number

        int n = random.Next(50);



        // print the number of console

        Console.WriteLine("Random number: {0}", n);

    }

}

Explanation

Inside the main() function:

  • Line 8: We instantiate the Random class and create an object called random.
  • Line 11: We generate a random number using the Next(int) method.
  • Line 14: We print the random number on the console.

3. The Next(int, int) method

This method generates a random number within the specified range. Here, the first integer acts as the lower bound and the second integer acts as the upper bound.

Syntax

Random random = new Random();

int num = random.Next(int, int);
Syntax of the Next(int, int) method

Example

Let's see an example of the Next(int, int) method in the code snippet below:

using System;



class Example

{

    static void Main()

    {

        // instantiate Random class

        Random random = new Random();



        // generate a random number

        int n = random.Next(20, 30);



        // print the number of console

        Console.WriteLine("Random number: {0}", n);

    }

}

Explanation

Inside the main() function:

  • Line 8: We instantiate the Random class and create an object called random.
  • Line 11: We generate a random number using the Next(int, int) method in the range (20, 30).
  • Line 14: We print the random number on the console.

4. The NextDouble() method

This method generates a random floating number within the range (0.0, 1.0).

Syntax

Random random = new Random();

int num = random.NextDouble();
Syntax of the NextDouble() method

Example

Let's see an example of the NextDouble() method in the code snippet below:

using System;



class Example

{

    static void Main()

    {

        // instantiate Random class

        Random random = new Random();



        // generate a random number

        double n = random.NextDouble();



        // print the number of console

        Console.WriteLine("Random number: {0}", n);

    }

}

Explanation

Inside the main() function:

  • Line 8: We instantiate the Random class and create an object called random.
  • Line 11: We generate a random floating number using the NextDouble() method.
  • Line 14: We print the random number on the console.

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