C# List Initialization

How to initialize a List<T> in C#

In this tutorial, you will learn how to initialize a list in C#. We will show you examples of creating an empty list and a list with initial values.

See also:

• Remove duplicates from a list in C#

Initialize a list in C#

Creating an empty list

To create a new empty list, you can write as follows:

List<DataType> variable name = new List<DataType>();

Example:

List<int> numbers = new List<int>();

Before you can use the List<T> class, you need to declare the following namespace:

using System.Collections.Generic;

Initializing a list

To initialize a new list with values, you can write as follows:

List<DataType> variable name = new List<DataType>() { value1, value2, value3, value4, };

Example:

List<int> numbers = new List<int>() {1, 2, 3, 4, 5, 6};

Examples of C# List<T> initialization

The following sample program is an example of List<T> initialization in C#:

using System;
using System.Collections.Generic;
namespace CSharp_List_Initialization
{
    public class Program
    {
        public static void Main(string[] args)
        {
            //Create an empty list
            List<int> list = new List<int>();
            Console.WriteLine("The number of elements: {0}", list.Count);
            //Add items to the list
            list.Add(1);
            list.Add(3);
            list.Add(2);
            list.Add(4);
            list.Add(5);
            Console.WriteLine("The number of elements: {0}", list.Count);
            //Print elements of the list
            Console.WriteLine("{0}", string.Join(",", list));
        }
    }
}
 

Output:

The number of elements: 0
The number of elements: 5
1,3,2,4,5

The following sample program shows how to initialize a list:

using System;
using System.Collections.Generic;
namespace CSharp_List_Initialization
{
    public class Program
    {
        public static void Main(string[] args)
        {
            //Create an empty list
            List<int> list = new List<int>() { 1, 2, 3, 4, 5 };
            Console.WriteLine("The number of elements: {0}", list.Count);
            //Print elements of the list
            Console.WriteLine("{0}", string.Join(",", list));
            //Add items to the list
            list.Add(6);
            list.Add(7);
            list.Add(8);
            list.Add(9);
            list.Add(10);
            Console.WriteLine("The number of elements: {0}", list.Count);
            //Print elements of the list
            Console.WriteLine("{0}", string.Join(",", list));
            //Remove
            list.Remove(6);
            list.Remove(7);
             Console.WriteLine("The number of elements: {0}", list.Count);
            //Print elements of the list
            Console.WriteLine("{0}", string.Join(",", list));
        }
    }
}

Output

The number of elements: 5
1,2,3,4,5
The number of elements: 10
1,2,3,4,5,6,7,8,9,10
The number of elements: 8
1,2,3,4,5,8,9,10

Summary

In this tutorial, you learned how to initialize a list in C#. There are two ways to create a list: an empty list or a list with initial values.