List<T>

Syntax

List<Type> list = new List<Type>();

Examples

List<string> fruits = new List<string>();
fruits.Add("apple");
fruits.Add("banana");
fruits.Add("cherry");

Console.WriteLine(string.Join(", ", fruits));  // apple, banana, cherry
Console.WriteLine(fruits.Count);                // 3

List<string> names = new List<string> { "Fola", "Zain", "Jamal" };

Console.WriteLine(names[1]);   // Zain

names[1] = "Priya";             // replace element at index 1
Console.WriteLine(string.Join(", ", names));

names.Remove("Jamal");           // remove by value
names.RemoveAt(0);                // remove by index
Console.WriteLine(string.Join(", ", names));  // Priya

List<int> numbers = new List<int> { 10, 20, 30 };

foreach (int num in numbers)
{
    Console.WriteLine(num);
}

Console.WriteLine(numbers.Contains(20));  // true
Console.WriteLine(numbers.IndexOf(30));    // 2

List<int> numbers = new List<int> { 5, 1, 3 };

numbers.Sort();
Console.WriteLine(string.Join(", ", numbers));  // 1, 3, 5

numbers.Sort((a, b) => b.CompareTo(a));  // descending, via a lambda
Console.WriteLine(string.Join(", ", numbers));  // 5, 3, 1

Best practices

• Use List<T> as the default resizable collection - it covers the vast majority of everyday collection needs in C#
• Declare the variable using the IList<T> or IEnumerable<T> interface in method signatures so the implementation can vary without changing calling code
• Use Contains() sparingly on large lists - for frequent membership checks, a HashSet<T> is much faster
• Specify an initial capacity (new List<int>(100)) when you know roughly how many elements to expect, to reduce internal resizing

At a glance

Purpose

Applications on the .NET platform

File extension

.cs

Runs in

.NET runtime

Usually used with

.NET SDK and libraries

Specifications & further reading

• C# language reference

Related C# documentation