This demo briefly explains how to get random element from a List<T> in C#. This example is a ASP.NET console program.

Source Code

Download source code here. This project was created in Visual Studio Community 2019.

Application Demo

Basically, the console simply displays a random string one line at a time. The random part will be either of these three strings: biology-1, biology-2, and biology-3.

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The Complete Program

static void Main(string[] args)
{
    // Initialize our list
    List<string> mylist = new List<string>(new string[] { "biology-1", "biology-2", "biology-3" });

    Random R = new Random();

    // get random number from 0 to 2. 
    int someRandomNumber = R.Next(0, mylist.Count());

    Console.WriteLine("Hello {0}", mylist.ElementAt(someRandomNumber));
    Console.ReadKey();
}

Brief Explanation of the Source Code

I created a list of strings initialized with 3 strings.

List<string> mylist = new List<string>(new string[] { "biology-1", "biology-2", "biology-3" });

To get a random element, what we want to do is use the ElementAt method of List<T>, like this,

mylist.ElementAt(someRandomNumber)

Like arrays, a list has elements whose position starts at 0 and ends at mylist.Count() - 1. In this program, we generate the value for someRandomNumber by using the Random.Next method

int someRandomNumber = R.Next(0, mylist.Count());

to get a random number from 0 to mylist.Count()-1. In my example, since I have three elements, I want a random number from 0 to 2. Element #3 does not exist!