How to populate a list with random integers in C#

Random numbers are crucial in various applications, ranging from simulations and games to cryptography and statistical analysis. In C#, the .NET framework provides a built-in library called System.Random that allows us to generate random numbers easily.

Let's look at how to populate a list with random integers in C#.

Using the Random class

To populate a list with random integers in C#, we can use the Random class to generate random numbers and add them to the list.

using System;
using System.Collections.Generic;
class Program
{
    static void Main()
    {
        List<int> randomNumbers = new List<int>();
        Random random = new Random();
        // Generate and add 10 random integers to the list
        for (int i = 0; i < 10; i++)
        {
            int randomNumber = random.Next(); // Generate a random integer
            randomNumbers.Add(randomNumber); // Add it to the list
        }
        // Print the random numbers in the list
        foreach (int number in randomNumbers)
        {
            Console.WriteLine(number);
        }
    }
}

Explanation

Let's take a look at the code above:

  • Line 8: We create an empty list named, randomNumbers, to store integers.

  • Line 9: We create an instance of the Random class named random to generate random numbers.

  • Lines 12–16: We use a for loop to generate 10 random integers and add them to the randomNumbers list using the Add method.

  • Lines 19–22: Finally, we iterate over the list using a foreach loop and print each random number to the console.

Note: Each time we run the program, we'll get different random numbers because the Random class generates pseudo-random numbers based on a seed value. If we want to generate different sequences of random numbers, we can provide a different seed value to the Random constructor.

Using LINQ

Another way to populate a list with random integers in C# is by using LINQ (Language Integrated Query) and the Enumerable.Range method, along with the Random class.

using System;
using System.Collections.Generic;
using System.Linq;
class Program
{
    static void Main()
    {
        Random random = new Random();
        // Generate a list of 10 random integers
        List<int> randomNumbers = Enumerable.Range(1, 10)
            .Select(x => random.Next())
            .ToList();
        // Print the random numbers in the list
        foreach (int number in randomNumbers)
        {
            Console.WriteLine(number);
        }
    }
}

Explanation

Let's take a look at the code above:

  • Line 9: We create an instance of the Random class named random to generate random numbers.

  • Line 12-: We use the Enumerable.Range method to generate a sequence of numbers from 1 to 10.

  • Line 13: We then use the Select method to transform each number in the sequence into a random integer generated by the random.Next() method.

  • Line 14: Finally, we convert the sequence to a list using the ToList method and store it in the randomNumbers variable.

  • Lines 17–20: We iterate over the list using a foreach loop and print each random number to the console.

This approach allows us to generate a list of random integers more concisely using LINQ.

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