List<T>.Item[Int32] Property

Definition

Namespace:

System.Collections.Generic

Assembly:

System.Collections.dll

Source:

List.cs

Gets or sets the element at the specified index.

public:
 property T default[int] { T get(int index); void set(int index, T value); };

public T this[int index] { get; set; }

member this.Item(int) : 'T with get, set

Default Public Property Item(index As Integer) As T

Parameters

index

Int32

The zero-based index of the element to get or set.

Property Value

T

The element at the specified index.

Implements

Item[Int32]

Exceptions

ArgumentOutOfRangeException

index is less than 0.

-or-

index is equal to or greater than Count.

Examples

The example in this section demonstrates the Item[] property (the indexer in C#) and various other properties and methods of the List<T> generic class. After the list has been created and populated using the Add method, an element is retrieved and displayed using the Item[] property. (For an example that uses the Item[] property to set the value of a list element, see AsReadOnly.)

Note

Visual Basic, C#, and C++ all have syntax for accessing the Item[] property without using its name. Instead, the variable containing the List<T> is used as if it were an array.

The C# language uses the this keyword to define the indexers instead of implementing the Item[] property. Visual Basic implements Item[] as a default property, which provides the same indexing functionality.

List<string> dinosaurs = new List<string>();

Console.WriteLine("\nCapacity: {0}", dinosaurs.Capacity);

dinosaurs.Add("Tyrannosaurus");
dinosaurs.Add("Amargasaurus");
dinosaurs.Add("Mamenchisaurus");
dinosaurs.Add("Deinonychus");
dinosaurs.Add("Compsognathus");

Dim dinosaurs As New List(Of String)

Console.WriteLine(vbLf & "Capacity: {0}", dinosaurs.Capacity)

dinosaurs.Add("Tyrannosaurus")
dinosaurs.Add("Amargasaurus")
dinosaurs.Add("Mamenchisaurus")
dinosaurs.Add("Deinonychus")
dinosaurs.Add("Compsognathus")

// Shows accessing the list using the Item property.
Console.WriteLine("\ndinosaurs[3]: {0}", dinosaurs[3]);

' Shows how to access the list using the Item property.
Console.WriteLine(vbLf & "dinosaurs(3): {0}", dinosaurs(3))

Remarks

List<T> accepts null as a valid value for reference types and allows duplicate elements.

This property provides the ability to access a specific element in the collection by using the following syntax: myCollection[index].

Retrieving the value of this property is an O(1) operation; setting the property is also an O(1) operation.

See also

• Count